The monastic communities of Mount Athos in Greece have been men-only for the last thousand years. But now a decision by the country's parliament to allow people over the age of 15 to change their gender without going through surgery has led them to fear that rule could be broken.

The conservative Greek Orthodox Church has reacted furiously to the new law, with one diocese, Kalavryta and Egialia, announcing it would ring funeral bells for three minutes ever day in protest. Bishop Amvrosios of Kalavryta said it was 'an outrageous inspiration to allow a person to change gender with a simple application, in a few minutes, contrary to what God gave humans' and called homosexuality a 'deadly sin'.

Now the heads of the 20 Mount Athos monasteries have written to the Greek government expressing their fears about the new law. 'In light of this legislation, we are full of unease as to what the future holds for us,' they said. 'It is another violation of God's law, just like existing legislation which permits cohabitation agreements between same-sex couples. If we do not resist, then our ancestors will rise from their graves.'

Conservatives have expressed alarm at the possible impact on the mental health of young people of the new gender law, which received 174 votes in Greece's 300-member parliament. However, Prime Minister Alexis Tsipras said: 'We are on the side of those who have no voice, or whose voice is stifled.'