Twenty-two people, most of them Togolese sports officials, were killed when a passenger helicopter exploded and crashed on Sunday at Sierra Leone's main international airport, aviation officials said.

The Russian pilot of the Russian-made Mi-8 helicopter survived the crash. The helicopter was operated by Paramount Airlines, which shuttles passengers between Sierra Leone's coastal capital Freetown and Lungi airport.

The helicopter was carrying a delegation of Togolese sports officials who had earlier attended an African Nations Cup soccer qualifying game played in Freetown between Sierra Leone and Togo. Togo won 1-0.

The cause of the accident was not immediately known. The helicopter came down in flames on an airport runway.

"There was an explosion on board the helicopter before it landed," Donald Bull, general manager of the Sierra Leone Airport Authority, told reporters.

Rescue workers were later seen trying to extricate the charred bodies of the victims from the burned crash wreckage.

Bull said most of those killed were Togolese and it is not immediately clear if there were any other nationalities on board. The victims did not include players from the Togolese national soccer team.

The Togolese sports officials had apparently chartered the helicopter to catch their flight back to Togo.

Paramount Airlines is one of two commercial companies that run helicopter services between Freetown and Lungi airport, ferrying passengers in a 7-minute flight over the Sierra Leone river.

The alternative slower route is to use rusting river ferries or local fishing boats.

British Prime Minister Tony Blair paid a one-day trip to Sierra Leone, a former British colony, last week as part of a farewell tour to Africa.

He held talks at Lungi airport with the presidents of Sierra Leone and Liberia and was made a paramount chief by local traditional rulers in recognition for having sent British troops to Freetown in 2000 to help speed the end of a brutal civil war.