Yemen's Shiite rebel leader escalated his attack against the country's embattled president on Sunday, calling him a "puppet'' of the United States and regional powers.

Abdel-Malik al-Houthi, backed by supporters of former President Ali Abdullah Saleh, vowed to send fighters into the southern part of the country where Abed-Rabbo Mansour Hadi has taken refuge against the rebels, Associated Press reported.

Al-Houthi said the move is aimed at fighting al-Qaida and other militant groups, as well as forces loyal to Hadi who are in the south.

His one-hour fiery speech came hours after his militia seized the country's third largest city of Taiz, an important station in its advance. He called Hadi a "puppet" to international and regional powers who want to "import the Libyan model" to Yemen. He named the United States, Israel, Saudi Arabia and Qatar as conspirators against Yemen.

"The decision (to mobilize) aims to confront the criminal forces, al-Qaida, and its partners and sisters, and all those who want to take cover in regions or using political pretexts," al-Houthi said.

The AFP news agency reported that Shiite militia had seized the city's airport, located in the southwest of the country. Citing unnamed security sources, it said 300 men — including Houthis in military uniform and their allies — deployed at the airport and reinforcements were arriving by air and land from the capital Sanaa.

Thousands of people took to the streets of Taiz to protest against the Houthis and Saleh loyalists, prompting the rebels to disperse them by firing into the air and beating them back with batons, the AP reported.

It comes the day after the Houthis called for a general mobilization against forces loyal to Hadi.

On Saturday, U.S. troops evacuated a southern air base after al-Qaeda seized a nearby town amid growing violence in the war-torn nation. About 100 American troops and special forces units were stationed at the Al Anad air base, near the southern city of al-Houta, which was seized by al-Qaeda's Yemen branch — considered the terror organization's most dangerous — on Friday.

In a statement, U.S. State department spokesman Jeff Rathke said: "Due to the deteriorating security situation in Yemen, the U.S. government has temporarily relocated its remaining personnel out of Yemen." He said there is "no military solution to Yemen's current crisis," and added: "We urge the immediate cessation of all unilateral and offensive military actions."

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