BANGKOK - THAILAND'S army deployed dozens of troops backed by armoured cars on Thursday to prevent protesters occupying runways that ministers were due to use to fly to a cabinet meeting, witnesses said.

Demonstrators said they would block both of the runways at Bangkok's old Don Mueang airport, which are shared by a nearby military terminal from where the ministers are meant to depart.

Anti-government protesters seized Don Mueang, from which a handful of domestic flights operate, on Thursday morning, two days after taking control of Bangkok's main Suvarnabhumi international airport.

No outsiders except government officials and ministers were allowed inside the military airport building, which is also home to the Thai Air Force, an AFP reporter saw.

Armoured vehicles equipped with machine guns guarded the entrances to the military airport and dozens of heavily armed soldiers manned checkpoints around the building.

The ministers are expected to fly to Chiang Mai to meet Prime Minister Somchai Wongsawat, who arrived in the northern city on Wednesday after his return to Bangkok from a foreign trip was blocked.

'We expected that the cabinet meeting could be held at Chiang Mai provincial hall this afternoon so we have been prepared,' Parntip Thongngamkham, the provincial spokeswoman, told AFP.

'Some ministers are already here,' she said.

Mr Somchai, a close ally of ousted former premier Thaksin Shinawatra, used a televised address on Wednesday night to reject a call by the powerful army chief to dissolve parliament and call fresh elections.

He said the cabinet meeting would discuss 'measures' to end the crisis but did not elaborate.

Protesters from the People's Alliance for Democracy have been campaigning against the government for months, saying it is corrupt and merely a proxy for Thaksin. -- AFP