Hundreds of Yemenis took to the streets of Sanaa Sunday to demand the withdrawal of Shiite rebels, in a first protest against the insurgents since they overran the capital last week.

In eastern Yemen, meanwhile, a suicide bombing struck a hospital used by the rebels, tribal sources said, without giving a casualty toll.

Yemeni President Abdrabuh Mansur Hadi Friday urged Shiite rebels who overran Sanaa at the weekend to pull out of the capital, accusing them of breaching a U.N.-brokered peace accord.

Hadi's call came as Washington ordered a cut in the number of American government staff in Yemen due to the "unpredictable" security situation, and an updated travel advice urged U.S. citizens in Yemen to leave.

The lightning takeover by Shiite rebels of Yemen's capital this week is a potential boost for Iran against its rival Saudi Arabia, while the U.S. is preoccupied with fighting jihadists, analysts said.

It is still unclear what the links are between the Ansarullah, or Huthi, rebels and Shiite-ruled Iran, but Tehran will no doubt be pleased by a move that offers the prospect of expanding its influence on the Arabian Peninsula.

President Abdrabuh Mansur Hadi warned Tuesday of "civil war" in Sunni-majority Yemen and vowed to restore state authority as Shiite rebels in apparent near-total control of Sanaa hailed their "victory".

Yemen "is facing a conspiracy" and "the danger of slipping into civil war", Hadi said in a speech at the presidential palace, two days after Ansarullah rebels took all other key state institutions in the capital, overshadowing a U.N.-brokered peace deal.

At least 200 people were killed on the outskirts of the Yemeni capital in fighting during the past week between Shiite rebels and Sunni militiamen, the government said Monday.

Rescue teams retrieved 53 bodies during the day, "bringing the total pulled by ministry teams since September 16 to 200 bodies," the health ministry said in a statement carried by Saba state news agency.

Shiite rebels guarded government offices and army bases in the Yemeni capital alongside troops on Monday after a U.N.-brokered peace agreement aimed at ending a week of deadly fighting.

Sunday's hard-won deal, signed by the president and all the main political parties, is intended to put the troubled transition back on track in impoverished Yemen which borders oil kingpin Saudi Arabia and is a key U.S. ally in the fight against Al-Qaida.

Fighting raged in the Yemeni capital on Sunday despite an announcement by the U.N. envoy that pro-government forces and Shiite rebels were poised to sign a deal.

The shelling and gunfire in the north of Sanaa was heard across the capital, as Sunni Islamist militiamen battled the rebels prompting an exodus of terrified residents, an Agence France Presse correspondent reported.

Flights to the Yemeni capital were suspended for a second day straight Saturday as the toll mounted from clashes between pro-government forces and rebels after U.N. efforts to reach a ceasefire ended.

Forces allied to the government have been battling to halt Shiite rebels who have swept into Sanaa from their stronghold in the rugged northwestern mountains.

Yemeni Shiite rebels agreed Friday to stop fighting Islamists and troops north of Sanaa which has killed dozens this week, in their campaign for a new government and greater political clout.

The fighting became so intense that, by Friday, international airlines suspended flights in and out of the nearby airport and state television stopped broadcasting after coming under fire.

The U.N. envoy to Yemen held talks Wednesday with Shiite rebel leader Abdulmalik al-Huthi in a fresh effort to end the country's political crisis, as deadly fighting intensified north of Sanaa.

Jamal Benomar flew to the rebel stronghold of Saada in an unexpected visit after failure to hammer out a deal between President Abdrabuh Mansur Hadi and rebels seeking greater political clout.