Tens of thousands of Yemenis marched Friday in the capital, Sanaa, in support of Shiite rebels who captured the city last year. The demonstrators denounced alleged "foreign conspiracies" — a reference to international backing for Yemen's embattled president, who managed to escape house arrest at the hands of the rebels earlier this month.

Meanwhile, rallies against the rebels known as Houthis took place in several other places across the country, including cities of Taiz, Hodida, Bayda and Dhamar.

The rival rallies underscored the depth of the crisis that has gripped Yemen after the Houthis overran Sanaa last September and declared in January that they have taken over the country.

President Abed Rabbo Mansour Hadi, who managed to escape Sanaa and house arrest at the hands of the rebels, has established a base in the southern city of Aden.

The international community has backed Hadi, and the U.N. envoy to the country is trying to negotiate a solution to the crisis, including relocating peace talks to outside of Sanaa. On Thursday, the Houthi rebel leader, Abdel-Malik al-Houthi, claimed Saudi Arabia and other international powers are pushing for a division of Yemen along regional and sectarian lines.

Hadi insists on keeping the country together. "Yemen will not have security without its unity," he told Aden TV on Friday.

Western and Arab countries have shut their embassies in Sanaa, with some relocating to Aden in a sign of support for Hadi. On Friday, the United Arab Emirates opened its mission on Aden, according to UAE minister of state for foreign affairs, Anwar bin Mohammed Gargash.

Yemen's deepening turmoil, with its threat of full-blown sectarian warfare between Shiites, who make up a third of the population and reside mostly in the country's north, and Sunni tribes in the south, has appeared to benefit al-Qaida's Yemeni branch, considered to be one of the terror network's most dangerous.

Al-Qaida militants have targeted both the Shiite Houthis on one side, and Yemeni officials and government troops on the other side.

On Thursday night, al-Qaida militants ambushed a military truck during a night-time attack in the southern province of Lahj, killing all four soldiers in the vehicle. Yemeni security officials, speaking on condition of anonymity because they were not authorized to talk to reporters, said the attackers surprised the soldiers with heavy gunfire.

Al-Qaida in the Arabian Peninsula, as the Yemeni branch is officially known, claimed responsibility in a statement posted on militant Twitter accounts. It said the militants set fire to the army truck after they seized the soldiers' machineguns.

Also Friday, a spokeswoman for the U.N. High Commissioner for Human Rights said the critical conditions in Yemen were being closely monitored with great concern as the political dialogue was faltering.

In Geneva, Ravina Shamdasani said the U.N. organization has documented a number of unlawful arrests, arbitrary detentions and targeting of journalists recently.

"It is crucial that all sides exercise restraint and work to resolve the political impasse in a peaceful manner and to avoid the situation from spiraling out of control," Shamdasani said.

AP