BANGKOK - Thailand's opposition Democrat Party will boycott a February 2 election, its leader said on Saturday, a move that could deepen uncertainty amid anti-government protests seeking to topple the government and thwart the poll.

"The Democrat Party found that Thai politics is at a failed stage," party leader Abhisit Vejjajiva, a former prime minister, told reporters in announcing the decision not to run.

"The Thai people have lost their faith in the democratic system."

Prime Minister Yingluck Shinawatra dissolved parliament on December 9 and called the snap poll in a bid to defuse tensions, but opposition against her remains strong and a mass rally is due to take place in Bangkok on Sunday.

Her Puea Thai Party is expected to win most votes in the poll, which the election commission said on Friday would go ahead as planned, despite concerns the poll could be marred by violence.