Sanaa: The airport in Yemen's capital was shut down on Saturday after forces loyal to a general close to former president Ali Abdullah Saleh threatened to attack landing and departing aircraft, an airport source said.

The airport has been surrounded by forces loyal to air force chief General Mohammed Saleh al-Ahmar, Saleh's half brother, who has refused to step down after being sacked by President Abdrabuh Mansur Hadi, the source said.

"No aircraft has taken off or landed since these forces made their threat late on Friday," the source said, adding that the troops surrounding the airport were backed by members of the Hamdan tribe that supports former strongman Saleh.

 These men were led by Naji Jamaan, a Hamdan tribal chief, the source added.

Ahmar has refused to step aside unless several senior defence ministry officials, including the minister himself, also leave, a military source said on Saturday.

 In a message to his troops, Ahmar said that Hadi's presidential decree would not be "implemented" until Defence Minister Mohammed Nasser Ahmed, General Ali Mohsen al Ahmar and chief of staff Ali al-Ashwal left their posts.

He also demanded that several members of the powerful Hashed tribe be forced into exile. The tribe backed defectors such as General Ali Mohsen al-Ahmar during last year's anti-regime protests.
On Friday, Hadi sacked the air force chief and the head of the presidential guard General Tareq Mohammed Abdullah Saleh -- the former president's nephew.

There had already been calls from within the air force for Ahmar to go.

 The military source said Saleh had turned down the command of the 37th battalion of the Republican Guard based in the southeast province of Hadramawt.

President Hadi took over from Saleh in February after the veteran leader, who had ruled for 33 years, handed over power as part of a Gulf-brokered settlement to end a bloody government crackdown on an Arab Spring-inspired uprising.

  In a televised speech on February 19, Hadi stressed the need to reunify the army as he pledged "radical reforms" and to fight Al-Qaeda as he outlined a two-year transition plan.

 But critics of Saleh say he has been interfering in the smooth transition of power, and the reorganisation of the army is seen as being a key part of that transition.