MEXICO CITY – The Roman Catholic Church on Sunday called on doctors in Mexico City not to perform abortions and lamented the city’s decision to legalize the procedure in the first 12 weeks of pregnancy.

The church has vowed to continue its anti-abortion campaign even through it is under investigation for possibly violating Mexican laws forbidding the church’s participation in politics.

Mexico City officials have said doctors at city-run hospitals cannot refuse to perform abortions based on personal moral objection, but in a letter read at Sunday Mass, Cardinal Norberto Rivera said they could.

“We call on all of those of good conscience not to be responsible for the abominable act,” the letter stated. “We remind the doctors, nurses, health care workers and all those affected by this unjust law, that they can invoke their human right to conscientious objection.”

Archdiocese spokesman Hugo Valdemar Romero has said doctors and nurses who performed abortions and lawmakers who supported the legalization will be excommunicated.

Mexico City Mayor Marcelo Ebrard, whose leftist Democratic Revolution Party backed the bill approved last week, said he would not be deterred by the church.

“We are in the 21st century, not the 16th,” Ebrard said. “I have a lot of respect for issues of faith. … But this is a case where the affairs of state reign.”

Elsewhere in Mexico, abortion is only allowed in cases of rape, danger to the mother’s life or severe fetal defects.