There was no immediate comment from Ethiopia's foreign ministry.

"We can hear explosions as it burns. It is burning like hell," an airport security officer said. Only a blackened shell of the plane remained after the fire was put out.

The AU peacekeeping force said four crew members were killed and two were in hospital.

In March, the UN Security Council partially lifted a decades-old arms embargo for one year to help the government buy light weapons to strengthen its military to fight the Islamist rebel group, al Shabaab.

The AU said the airport, home to a growing number of passenger flights since African troops and Somali government forces flushed al Shabaab rebels from their bases in the capital two years ago, would resume operations soon. It gave no details on what caused the plane to crash.

Military aircraft regularly land at the city's airport, which also serves as the headquarters for the AU peacekeepers.

Ethiopia sent forces inside Somalia in 2011 to open up a new front in the military campaign to crush the al Shabaab insurgents and end their six-year fight to impose a strict interpretation of Islamic sharia law on the country.

But the Addis Ababa government is frustrated by the slow pace at which the 17,700-strong AU force and Somali troops have backfilled areas liberated from al Shabaab.

Earlier this year Ethiopia threatened to pull its soldiers out.

Somalia's aviation record is among the worst on a continent that has a history of plane disasters.

Until recently, the carcass of another Russian-made cargo plane lay tilted on its belly near the passenger terminal of Mogadishu's airport.