BANGKOK, Thailand - Thailand's revered king urged the prime minister Thursday to keep his promises to do good for the nation in a televised meeting that could undercut plans for a massive demonstration to call for the government to step down.

The protesters, spearheaded by the People's Alliance for Democracy, claim the government of Prime Minister Samak Sundaravej is a proxy for former Prime Minister Thaksin Shinawatra, ousted by a 2006 military coup.

The alliance led mass demonstrations before the coup demanding Thaksin step down for alleged corruption and abuse of power.

They now accuse Samak's government of interfering with corruption charges against Thaksin and trying to change the constitution for its own self-interest.

Although facing criminal charges for alleged corruption, Thaksin remains a powerful figure in Thailand.

The demonstrators _ claiming their ranks will swell to 100,000 Friday as reinforcements converge from across the country _ have been in Bangkok's streets for the past three weeks.

They have pledged to ring Government House, where the prime minister's offices are located, until Samak's administration resigns.

Police said they would not be allowed to march there from their current rally site nearby.

King Bhumibol Adulyadej addressed Samak when the prime minister presented two new Cabinet ministers to take their oaths of office, and the address was broadcast on the evening television news, as is normal for such occasions.

"I expect that you will do what you have promised and when you can do that, you will be satisfied," the king said. "With that satisfaction, the country will survive. I ask you to do good in everything, both in government work and other work so that our country can carry on and people will be pleased."

The king's address to Samak and his appointees was about five minutes long and was not critical of the government.

Coming on the eve of the planned protest, it could be to Samak's advantage as it suggested his government's legitimacy. The protesters have repeatedly asserted they are defending royal interests.

Suriyasai Katasila, one protest leader, said more than 100,000 people were expected to gather Friday.

"People are coming from everywhere," he said. "They want to show their solidarity with us and they want to express their discontent with the government who has been serving no one but themselves."

Samak's People Power Party won general elections last December. His Cabinet is packed with Thaksin's allies and critics say rehabilitating the former leader is among the government's top priorities.