Judges of the Constitutional Court had to scurry to a suburban courtroom where they are to decide whether Prime Minister Somchai Wongsawat and others in his party committed electoral fraud - a move that would see him banned from politics and his party dissolved.

Hours earlier, an explosive device was hurled into a crowd of anti-government protesters at Bangkok's domestic airport, killing one person and wounding 22, said Surachet Sathitniramai of the Narenthorn Medical Centre.

The court is expected to rule this week, and if the decision goes against Mr Somchai it could dampen protests by the People's Alliance for Democracy (PAD), which has been seeking his ouster through daily protests and the seizure of Bangkok's domestic and international airports.

But it could also inflame pro-government supporters who have been gathering their strength in recent days and widen an already dangerous rift in Thai society, further paralysing government machinery and draining the economy of millions of dollars.

The PAD on Monday abandoned the compound of Government House and moved protesters to Don Mueang and Suvarnabhumi airports that it had taken over.

Maj-Gen Chamlong Srimuang, one of the PAD's core leaders, said that all five PAD leaders agreed to do so not because of pressure from any party, but because it was time for them to vacate the place after occupying it since August 26. The move was also intended to accommodate royal ceremonies, including today's Trooping of the Colour, to commemorate His Majesty the King's 81st birthday on December 5.