A Catholic diocese in southern Mexico has withdrawn all of its nuns from the violence-ridden city of Chilapa following the killing of two of its priests earlier this month.

Two priests were killed in the diocese of Chilpancingo-Chilapa at the beginning of February, while the diocese said the parents of one of its nuns had also been killed, as well as a school having to shut down due to the threat of local drug gangs, according to Associated Press.

The nuns, believed to number four, ran one of the oldest and most respected schools in Chilapa, the diocese said.

Their statement urged the end to gang violence, expressing hope that others might be able run the school in the nuns' stead.

'We call on the criminal gangs not to affect or destroy one of the sacred things we have: the education of our children and youths,' the statement said.

On February 5 two priests were shot to death and four others wounded when their van, travelling home from a concert in a nearby town, was attacked by gunmen who then fled the scene.

'We call on the authorities, that once the truth is known, that justice be served,' a statement from the Archdiocese of Acapulco said following the news.

It went on to call for prayer for 'the conversion of those who, forgetting that we are brothers, commit this kind of crime, which injures the dignity of the human person so much, snatches away the sacred gift of life and sows pain and suffering in the family and in society.'

'Let us not relent in our efforts to build peace in our family, in our community, in our state, in our homeland. Let us ask the Lord for this peace every day.'