Saudi fighter jets have pounded the strongholds of Houthi combatants in northern Yemen as an earlier confrontation between Muslim fighters and Saudi security forces killed two Saudi security men.

Houthi spokesman Mohammed Abdel-Salam told The Associated Press that the Saudi offensive early Thursday struck at least four areas inside Yemeni territory using phosphorus bombs. There was no immediate word on the casualties.

There was no immediate official confirmation of the report from Riyadh or the Yemeni capital, Sana’a.

Saudi Arabia said on Wednesday that two security officers were killed and 10 others were wounded after Houthi combatants seized control of the village of al-Khawbah at the Jizan region in a cross-border clash.

Saudi Arabia was allowing the Yemeni army to use the mountainous area to launch attacks against the Houthi resistance fighters. The raid was in response to Riyadh’s continued support of Yemeni armed forces in the conflict zone, the Houthis said.

The Yemeni government launched Operation ‘Scorched Earth’ on August 11 to uproot the Muslim Houthi fighters, whom Sana’a accuses of seeking a return to the ‘Zaidi imamate’ overthrown in a 1962 coup.

The northern combatants however say that they have suffered religious discrimination by the Yemeni government.

Saada and neighboring Amran provinces are encircled by fighters and frequently pounded by military fighter jets and helicopter gunships. The conflict zones in northern Yemen remain cut from the rest of the country, and are currently grappling with a pressing shortage of food and other basic supplies.

The United Nations puts the figure of displaced people in northern Yemen at around 150,000 civilians.

Muslim fighters in north Yemen declare readiness to open humanitarian corridors for thousands of civilians driven out of their homes by fierce battles in the region.

In a statement posted on the Internet, the Houthi fighters said they would secure routes linking the camps for the displaced, but urged that the corridors be directly controlled by the United Nations.

The anti-government forces demanded a guarantee that the authorities would not use the routes to send in reinforcements for the Yemeni troops in the north.

The UN appealed on Sunday for the protection of the homeless civilians, in line with the international humanitarian law, warning that women and children accounted for 80 percent of the most vulnerable.

The feuding sides must “allow us to reach those who need assistance, rapidly and without hindrance,” the world body’s humanitarian chief, John Holmes, emphasized at the end of a three-day visit.

Some 150,000 people have been displaced or affected by the conflict since 2004, more than one-third of whom have fled since the army’s latest offensive against the Houthi fighters in the northern Saada province.

The Yemeni army launched a massive operation near the border with Saudi Arabia on August 11 to crush Houthi Muslims who accuse the government of neglect and discrimination against Yemen’s Houthi minority, accounting for almost 30 percent of the country’s population.

A Yemeni-based UN refugee officer, Andrew Knight, said about 65,000 displaced people are in the northwestern province of Hajjah, and an estimated 55,000 people are still living in Saada, mostly in abandoned buildings, in the mountains, and on roadsides in the war zone, The Los Angeles Times reported.

This is while Mazraq camp in Hajjah, the only UN camp for the displaced Yemenis, has no running water, electricity or even bathrooms, leaving about 40 percent of camp residents suffering from diarrhea. Nearly 20 percent of the children are malnourished in the relief center, where the spread of malaria has become a growing concern.

The Sana’a government has been plagued by massive protests in the south, where people are calling for a return to their formerly independent South Yemen, prior to the unification of the north and the south in 1990.

As Yemen continues its military campaign against the Houthi fighters in the north, US President Barack Obama offers assistance to battle Shia Muslims.

On Sunday, President Ali Abdullah Saleh received a letter from Obama, which pledged economic aid and assistance in fighting terrorism, the Yemeni SABA news agency reported.

“The security of Yemen is vital for the security of the United States,” said Obama in the letter, which was delivered to Saleh by the assistant for homeland security and counterterrorism John Brennan.

In the letter, Obama hailed what he called the partnership between the two countries in fighting terrorism and said that the Shia Muslims organization poses a common threat to everyone.

The US president also said that Washington would adopt a new initiative to help Yemen confront “development challenges and supporting reform efforts,” along with the International Monetary Fund, the World Bank, donor states and the Gulf Cooperation Council.

Obama’s letter came as the Yemeni government forces once again breached a temporary truce with the Zaidi Shia fighters they are fighting with in the north.

Since 2004, the Yemini army and the Zaidi Shia fighters have been engaged in violent periodic clashes, in a war which has claimed the lives of thousands and displaced up to 15,000 civilians- based on UN High Commission for Refugees estimates.

After just over a year of relative peace, a fifth round of fighting erupted on August 11, as the Yemeni government decided to launch a new wave of attacks against the northern provinces of Sa’dah and Amran.

Since then, several attempts have been made to restore truce between the two sides, but the government has renewed the fighting.

The Yemeni government accuses the Houthis of trying to restore a Zaidi imamate system, which was overthrown in a 1962 coup.

The rebels, however, say they are defending their people, which make up around 40 of Yemen’s population, against religious oppression and fighting for their civil rights.

The conflict has also affected other regional states, as San’a has accused Iran, Libya and Iraq of providing the fighters with weapons- allegations that have been denied by all three countries.

The rebels have also claimed that Saudi Arabia is “directly supporting” the government’s military offensive by providing it with different types of weapons, military vehicles and financial aid.

A website for Houthi fighters recently released new footage of what they say proves that the Yemeni army is using Saudi Arabian weapons.

Meanwhile in Iraq, Independent MP Izzat Shabandar lashed out at San’a on Monday, calling its accusations “ridiculous” and charging that Yemen has created a sanctuary for Saddam Hossein loyalists and al-Qaeda leaders.

After Pakistan, Yemen is seen as the primary haven for al-Qaeda militants, who are using the country to organize and train more recruits.

Although there was no mention in the SABA report of Obama making any specific reference to the conflict with Houthi fighters, it did point out that the US president had touched upon the need to fight al-Qaeda.

Last month, Yemeni forces launched anti-terrorist operations in a tribal area known as an al-Qaeda safe haven.

However, after a short while and without reaching any significant results, they ended the operation claiming that it was more imperative to address the situation in the north.

Obama’s offer to help fight Al-Qaeda to Sana’a – which has not demonstrated a strong detrmination to eradicate the terorist group -comes as the latest opinion polls indicate that most Americans are opposed to US “war on terrror” in Afghanistan.

A recent national poll published by the CNN showed that 57 percent of Americans are opposed to the Afghan war, while only 42 percent of respondents approve of Washington’s alleged military campaign against the Taliban and their al-Qaeda allies.

US-led forces invaded Afghanistan in 2001 to allegedly eradicate militancy and arrest militan leaders .More than 8 years after the invasion, top Taliban and Al-Qaeda leaders arre still at large.