Yemeni security forces have foiled a plot to carry out 10 suicide bombings against government buildings in the capital Sanaa, the defense ministry's news website reported on Monday.

A wave of arrests targeting a suspected al-Qaida cell held responsible for a May attack that killed more than 100 soldiers in the capital netted the 10 militants charged with carrying out the bombings, the 26sep.net website quoted "informed sources" as saying.

At least 16 gunmen have been killed in three days of fighting between Shiite Houthi rebels in north Yemen and Sunni Salafist extremists, according to claims by both sides on Tuesday.

"Four of our men were killed and six others wounded in confrontations on Saturday with Salafist gunmen in Al-Qobaaf," east of the Houthi stronghold of Saada, said Huthi spokesman Mohammed Abdulsalam.

Yemen will ask donors for about $10 billion in urgent aid at a "Friends of Yemen" meeting to be held in the Saudi capital later this month, the country's planning minister said on Wednesday.

"We are talking about $10 billion that we will need for economic recovery, to stabilize the economy and the currency," Mohammed Said al-Saadi told AFP on the sidelines of a donors conference in Sanaa.

The United States on Saturday praised Yemen's president for steps taken as part of the ongoing political transition even as the capital's airport was temporarily shut down and tensions ran high in Sanaa.

"The United States welcomes President Abd Rabo Mansour Hadi's announcement of civilian and military personnel transfers as part of the ongoing political transition in Yemen," State Department acting spokesman Mark Toner said.

The Yemeni army shelled suspected hideouts of al-Qaida militants in the southern province of Abyan, killing five of them, a local official told Agence France Presse on Tuesday.

"Five al-Qaida fighters were killed and several others wounded in the late Monday bombardment of al-Quz," on the outskirts of the provincial capital Zinjibar, which the militants overran last May, the official said.

Two gunmen shot dead on Sunday a U.S. citizen who worked at a language school in Yemen's second city of Taez, a security official said.

The assailants rode a motorbike in their attack on the man, who was the deputy director of a Swedish language center in the city, 270 kilometers (173 miles) southwest of Sanaa, the official said on condition of anonymity, adding they fled the scene after the shooting.

Air strikes that residents said were carried out by U.S. warplanes killed 27 suspected al-Qaida militants in mountains south of the Yemeni capital, local officials said on Saturday.

"They were new recruits, youths from the region, taken by surprise by the raids which struck as they were dining in training camps" on Friday night, one official said, on condition of anonymity.

A Lebanese expatriate, who works in an oil company in Yemen, has been released by his captors on Tuesday, reported the National News Agency.

Foreign Minister Adnan Mansour received news of his release, it added.

In a dimly lit tent in Yemen's Change Square, Nobel peace laureate Tawakkul Karman has laid out a blueprint of her country's future: a modern state with equality and rule of law.

Karman, a passionate 32-year-old, has toned down her once inflammatory rhetoric, no longer demanding President Ali Abdullah Saleh be brought to international justice, and throwing her support behind Vice President Abdrabuh Mansur Hadi, who will replace Saleh after Tuesday's election.

U.S. Deputy National Security Advisor John Brennan met with Yemen's vice president on Saturday and expressed Washington's commitment to provide support to the troubled country, official reports said.

"The U.S. will stand side by side with Yemen as it works to emerge from these difficult circumstances," the official SABA news agency quoted Brennan as saying in a meeting with Abdrabuh Mansur Hadi in Sanaa.