Clashes at Sanaa airport between Yemeni police and Shiite rebel gunmen have left three dead, in a rare confrontation since the rebels overran the capital in September, a security official said Tuesday.

Two policemen and a civilian were killed in the clashes that erupted overnight between police and armed men based at the airport since the northern rebels seized the capital unopposed on September 21.

The gunfight caused a brief interruption of air traffic, the official said.

It followed a strike by airport staff who demanded the withdrawal of the rebel gunmen from the airport.

Complaints have recently been made by Western embassies that rebels stationed at the airport have opened their diplomatic mail, violating international conventions, sources at Yemen's foreign ministry said.

The militiamen have also been insisting on boarding planes for inspection, aviation sources said, causing several airlines to delay resuming flights to Sanaa that were suspended on September 19 for security reasons.

The rebels remain the main force in the capital.

A UN-brokered agreement reached in September stipulated that the Huthi rebels, also known as Ansarullah, would withdraw from Sanaa once a new prime minister is named.

But they have rejected a new cabinet formed on Friday, insisting on a reshuffle that would keep out officials that they accuse of corruption.

Since they overran Sanaa, the Huthis have expanded their control to coastal areas and regions south of the capital, where their fighters have met fierce resistance from Sunni tribes and Al-Qaeda.

The turmoil has raised fears the Arabian Peninsula nation, which neighbours oil-rich Saudi Arabia and lies on the key shipping route from the Suez Canal to the Gulf, may become a failed state.