MANILA (Reuters) - The Philippine government’s chief lawyer on Monday filed a petition to remove the Supreme Court’s top judge, as an “act of kindness” to spare her the indignity of an impeachment trial that congress is set to vote on soon.

Maria Lourdes Sereno, the first woman to head the 15-member Supreme Court, is on an indefinite leave of absence to prepare for a trial in the Senate, should the lower house decide to impeach her for non-disclosure of income.

The case is another public challenge to a judge fiercely disliked by President Rodrigo Duterte, who has been unhappy about Sereno voting against some of his proposals, which still passed.

Sereno was appointed by Duterte’s predecessor.

Solicitor-General Jose Calida, an ally of Duterte, said he had asked Sereno’s Supreme Court peers to cancel her 2012 appointment for violations of court rules and procedures.

“This is the proper remedy to question the validity of Sereno’s appointment,” Calida told reporters after filing a “quo warranto” case questioning her right to hold her office.

“This is an act of kindness to a fellow lawyer,” he said, adding that he did not want Sereno “to undergo the indignity” of her predecessor, Renato Corona, who was removed in a Senate trial for concealing assets.

If congress decides to impeach an official, then the upper house, which currently has 23 members, convenes for a trial. Removal of an official requires a two-thirds vote.

Josa Deinla, a spokeswoman and lawyer for Sereno, said the legal window for Calida to file his case questioning her suitability expired in 2013 a year after she started the job.

“They just want to short-cut the process, betraying their anxieties that they will lose in the impeachment trial,” she said.

In October, Duterte dared Sereno to open her bank account to public scrutiny, accusing her of corruption and of being used by political opponents intent on driving him from power.

Sereno denies wrongdoing and has not responded publicly to Duterte’s verbal attacks.

Duterte’s critics believe the impeachment move is motivated by the administration being uncomfortable with the fact she is due to hold the Supreme Court’s top post until 2030, when she reaches the mandatory retirement age of 70.

Minority lawmaker Edcel Lagman said Sereno was on the receiving end of a “double barrel” assault to oust her, adding that she had committed no impeachable offence.