BANGKOK – A blast at Bangkok's international airport and grenade attacks elsewhere in the city wounded at least seven people on Wednesday, as lawlessness spread amid anti-government protests, officials said.

The explosion at Suvarnabhumi Airport happened a day after demonstrators stormed the airport, forcing it to close down and stranding thousands of passengers.

"At least two people were wounded by a bomb blast at Suvarnabhumi this morning," Petpong Kamchornkitkarn, an emergency medical services official, told AFP.

Two local television stations said a grenade was fired at protesters and that three people were wounded.

A near simultaneous grenade attack on anti-government protesters picketing Bangkok's old Don Mueang airport, where the prime minister has set up temporary offices, wounded two more people, Petpong said.

Another three people were wounded when two grenades were tossed into a crowd of pro-government supporters on a road to Don Mueang, the site of a clash between rival activists that left 11 hurt on Tuesday, police said.

Prime Minister Somchai Wongsawat moved to premises at Don Mueang after demonstrators occupied the government's main offices in central Bangkok in August.

The People's Alliance for Democracy, a protest movement, has led a six-month street campaign against the democratically elected government.

At least 3,000 passengers remained stranded at Suvarnabhumi early Wednesday as anti-government protesters kept control of the building, the airport chief said.

"There are 78 outbound and incoming flights affected. I have been informed by Thai Airways that 3,000 passengers are stranded at the terminal now," airport director Saereerat Prasutanont told AFP.

"Operations at Suvarnabhumi Airport have been totally shut down since 4am (2100 GMT Tuesday) both outbound and inbound after protesters refused to negotiate with anyone except the prime minister," said Saereerat.

He said passengers were unable to leave the terminal because guards from the PAD had sealed off entrance roads to the airport.

Protesters forced the airport to close on Tuesday as demonstrations in the Thai capital descended into violence with 11 injured in clashes.

Thousands of demonstrators breached police lines and stormed the airport -- a major hub for millions of travelers -- in their effort to pressure Somchai's government to resign.