BANGKOK, Feb 2 (Reuters) - Activists in Thailand filed a petition on Friday seeking life bans for dozens of lawmakers of the Move Forward party, the latest in a series of moves to stifle a popular opposition that tried to review a tough law against insulting the monarchy.

Complaints were submitted to the anti-graft commission to ban 44 Move Forward politicians for life, alleging serious breaches of ethics in backing a once unthinkable plan to amend one of the world's strictest lese majeste laws.

The Constitutional Court on Wednesday ruled Move Forward must abandon its proposal to review article 112 of the criminal code, which carries jail terms of up to 15 years, saying it seriously undermined the monarchy.

Thailand's constitution enshrines the king in a position of "revered worship" and royalists regard the palace as sacrosanct.

"These actions are a legacy of sins," petitioner Sonthiya Sawadee said of Move Forward's plan.

"They have not given up on amending article 112, meaning that they are still intent on overthrowing the democratic regime of government with the king as the head of state."

Move Forward won last year's election on a wave of youth and urban support for a progressive platform that included undoing business monopolies and curbing the military's entrenched political influence.

But its taboo-breaking bid to amend article 112 outraged conservatives and saw it blocked, opens new tab
from forming a government by lawmakers appointed by the royalist military.

Despite being in the opposition, Move Forward is the biggest party in parliament, with an anti-establishment agenda that is colliding with interests of powerful conservatives, old money families and generals.

Friday's complaint targets 44 Move Forward legislators - 29 current and 15 former.

It was not immediately clear if the anti-graft body, which has a remit beyond corruption, will investigate the complaint, which was the second against the party in as many days.

On Thursday, an activist lawyer whose petitions toppled politicians, including a prime minister, filed a complaint seeking Move Forward's dissolution and bans for its leadership.

Move Forward's website on Friday no longer included lese majeste law amendment among its policies.

"We are ready to defend ourselves ... reviewing laws is the responsibility of legislators," deputy leader Sirikanya Tansakul told reporters.

"We are not worried because we have evidence to show we have not breached ethical standards."