Yemeni President Abed Rabbo Mansour Hadi made the appeal Tuesday and warned that the advancing Shiite Houthi rebels who drove his government from the capital last month were in danger of overrunning the rest of the country.

"The Yemeni people have never faced such heinous aggression," Hadi said. "The threats posed by the Houthis are not targeting the security of Yemen but the regional and international peace and security."

The UN Security Council, most Western countries and Arab monarchies around the Gulf have backed Hadi as the country's legitimate ruler from his exile in the southern city of Aden.

But to the Shiite Muslim Houthis from the mountainous north, he is a pawn of Gulf Arab countries. The Houthis are accused of being funded by Shiite Iran and have warned they would resist any outside interference.

"We express our total and utter rejection of any external interference in Yemeni affairs under any pretext and in any form and from any side," the Houthi-allied Higher Committee to Preserve the Armed Forces and Security said in a statement on Wednesday.

Houthi forces on Wednesday captured an airbase 60 kilometers from Aden, just days after the US military evacuated soldiers stationed there.

Dangers of a proxy war between Iran, Saudi Arabia

With fighting intensifying, the conflict risks turning into a proxy war with Shiite Iran backing the Houthis and Saudi Arabia and other Sunni Muslim monarchies backing forces loyal to Hadi.

That was underlined by reports of a "significant" Saudi military buildup along its 1,800-kilometer (1,100-mile) frontier with Yemen.

Saudi Arabia's Foreign Minister Saud al-Faisal warned that "if the Houthi coup does not end peacefully, we will take the necessary measures for this crisis to protect the region."

Houthi forces are continuing to move south towards Hadi's stronghold in Aden, with warplanes pounding his compound in recent days.

War spilling into the streets

At least five Sunni demonstrators displeased with the Houthi advance in the city of Taez were killed Tuesday by Houthi rebels in what rights groups called a "shocking disregard for human life."

"Human rights in Yemen are in free-fall as even peaceful protest becomes a life-threatening activity," warned Said Boumedouha, the deputy director of Amnesty's Middle East and North Africa program.

Hadi came to power in 2011 following an Arab Spring-inspired uprising. He was installed following a deal brokered by the UN and Gulf countries the following year, but he has suffered from a crisis of legitimacy among the predominately Shiite Houthi in Yemen's north. Houthi rebels took control of the capital, Sanaa, but Hadi escaped from his house arrest and re-established himself as president in the southern port city of Aden.

Hadi's government has supported the United States' deadly drone strikes against al Qaeda affiliates, but the recent fighting has undermined his government's ability to combat religious extremists, who could undoubtedly exploit any security vacuum created by a civil war.

jar/sms (AP, AFP, Reuters)