Four explosions rocked an air base in Sanaa on Sunday, setting two fighter jets on fire and prompting the closure of the Yemeni capital's international airport, aviation officials said.

"There were four explosions at the air force base alongside the international airport and two fighter jets went up in flames," the official told AFP on condition of anonymity.

Sanaa international airport closed after the explosions, another aviation official told AFP on condition of anonymity.

"The airport was closed right after the explosions ... All flights have been re-routed to Aden," the south's main city, the official said.

Residents of the airport district area reported loud explosions and massive flames and plumes of smoke.

There were no immediate reports of casualties and no claims of responsibility for an attack.

Sanaa has been the scene of deadly clashes between troops loyal to President Ali Abdullah Saleh, and dissident soldiers and armed tribesmen who have thrown their support behind protests that have rocked his regime since January.

Tens of thousands of demonstrators have risked their lives in near daily protests that have been met with force by pro-Saleh troops. Hundreds of people have been killed and thousands more wounded over the past nine months.

On Friday, marchers in Sanaa demanded Saleh go on trial over the killings.

"O men who love peace in the world, Saleh must face justice," chanted a crowd of 10,000 people that amassed after weekly Muslim prayers in Sittin Street, near Change Square, the epicentre of anti-regime demonstrations.

The opposition accuses the longtime president of nepotism and corruption, but the strongman has refused to step down despite pressure from Gulf nations and the UN Security Council.

Last Tuesday, Saleh told the US ambassador in Sanaa that he is committed to a Gulf plan to step down, the State Department said.

State Department spokeswoman Victoria Nuland welcomed Saleh's remarks but said that he needed to live up to his promises, after a string of statements by the veteran leader voicing support for the plan without implementing it.

Saleh met with US Ambassador Gerald Feierstein to discuss developments in Yemen after the Security Council and the United States both urged him to begin the transfer of power immediately, Nuland said.

Under the plan brokered by the Gulf Cooperation Council, Saleh would step down 30 days upon signing of the deal in exchange for immunity from prosecution.