MANILA - Opposition Senators Leila de Lima and Antonio Trillanes IV have sought inclusion in the Supreme Court's proceedings on the petition to nullify Chief Justice Maria Lourdes Sereno's appointment, seeking the dismissal of the Solicitor General's case.

The two senators filed a motion before the High Court asking permission to allow them to intervene in the proceedings on the "quo warranto" plea earlier filed by Solicitor General Jose Calida to seek Sereno's ouster.

• SolGen defends quo warranto: Sereno impeachment excludes ineligibility

Sereno, who is also facing an impeachment case, had earlier asked the court to throw out the Solicitor General's plea, arguing that she could only be removed through impeachment proceedings.

• Sereno urges SC to junk quo warranto petition seeking her ouster

She is currently on indefinite leave to prepare for a possible impeachment trial at the Senate.

On Tuesday, Sereno's fellow Supreme Court magistrates decided to hold oral arguments on the quo warranto plea against her on April 10 in Baguio City.

• SC to hold oral arguments on quo warranto plea seeking Sereno's ouster

A spokesperson for Sereno on Wednesday confirmed that the chief magistrate would attend the proceedings.

Sereno's attendance would mark the first time that a sitting chief justice would take questioning from her colleagues in oral arguments.

• Sereno to attend oral arguments on quo warranto plea

-- with a report from Ina Reformina, ABS-CBN News