MANILA- The Supreme Court's decision to remove Maria Lourdes Sereno as chief justice "diminished our democracy," the Commission on Human Rights (CHR) said Tuesday.

In a statement, the agency criticized the ouster of the country's first female top magistrate via a "quo warranto" petition as it insisted that impeachment is the sole way to remove a justice of the high court.

"We are in disbelief that majority of the members of the Supreme Court has decided to remove Chief Justice Maria Lourdes Sereno by granting the quo warranto petition, a means unsanctioned by the Constitution," it said.

"Our Constitution is clear: a sitting Chief Justice can only be removed through impeachment. And a quo warranto petition cannot supplant this," it added.

The Supreme Court last Friday granted Solicitor General Jose Calida's quo warranto petition against Sereno, invalidating her 2012 appointment as chief justice.

• Supreme Court ousts Chief Justice Sereno
• Supreme Court declares Chief Justice post vacant

In its ruling, the high court said its grant of a quo warranto plea to oust Sereno as chief justice seeks to ensure that “only qualified individuals” hold public office.

• SC: Quo warranto remedy ensures only 'qualified' hold public office

Sereno was supposed to remain chief magistrate until her retirement at age 70 in 2030.

Her removal from office marks the first time in Philippine history that a chief justice was ousted through a quo warranto plea.

• SC: Quo warranto remedy ensures only 'qualified' hold public office

"This decision has diminished our democracy. It erodes our obedience to the rule of law and departs from the will of the Filipino people," the CHR said.

The commission also noted that the core value of the Constitution lies in the system of checks and balances.

"Upholding the 1987 Constitution means protecting the Filipino against abuse and concentration of power," it said.

Sereno is set to appeal her ouster.

• Sereno to appeal her ouster