Thai Prime Minister Samak Sundaravej on Monday accused anti-government protesters of trying to destroy the economy, and told the nation he would only resign if a court ordered him to.
A coalition of groups claiming allegiance to the revered monarchy have called for a massive protest on Tuesday, with local press reporting that they plan to block major roads into Bangkok and surround Government House.
Samak, who formed a coalition government in February and has been battling street rallies since May, warned that any violence would not be tolerated.
"The movement tomorrow should be abide by the laws ... if it goes beyond the boundaries of the law, police will handle it," he told a press conference.
"This government comes from legal elections. If someone want to overthrow the government, they should ask parliament," he said in comments broadcast live on TV.
"About cases in the court process, if I have to quit, I will quit ... I am confident whatever happens, I can accept it. Whatever happens, it will not affect this country."
Samak's People Power Party, which is made up of former allies of ousted premier Thaksin Shinawatra, is being investigated for electoral fraud which could see the Constitutional Court dissolve the party.
The prime minister is also awaiting a ruling from the Appeals Court on a defamation charge he was facing before his election last December.
Protests led by the so-called People's Alliance for Democracy (PAD) have rumbled on since May, sparking rumours of another coup and sending jittery investors away from the Thai stockmarket.
The PAD is demanding that Samak step down, as its claims he is running the country on behalf of Thaksin, who was ousted in a 2006 coup.
"They don't think about the country (but) I can be patient if they want to destroy the economy," Samak said.
"But when they said they will call for a big demonstration, people panic. It may be a riot," he added.