Unite said many ministers and other church workers had faced problems with drunks or intruders over the festive season in recent years.

The union claimed that the main problem was that churches have no legal responsibility for the safety of the clergy, who are deemed to be employed by God.

Unite is campaigning for better employment rights for ministers, including improved safety.

The problem affected Methodist, Catholic and Church of England ministers, said the union.

Officials said there had been a number of attacks in recent weeks on church employees in parts of the country, including Liverpool and Newcastle.

Rachael Maskell, national officer of Unite, said: "Ministers are very visible and often alone in their churches, with their homes advertised as being the vicarage and their dress making them easily identifiable.

"It only takes one individual to take advantage of this situation in search of money or looking for trouble to blight the life of a minister.

"We know of many cases where individuals have had to confront unwanted guests. This Christmas, we are advising all church ministers to ensure that they safeguard their own well-being by not being alone in their churches."

The Rev Malcolm Liles, from Crawley, in Sussex, who is a member of Unite, said: "While we welcome all to church over the Christmas period, we are aware that some individuals take advantage of the season of goodwill and use it for ill will. I have heard of several instances where clergy have been asked for money or have been assaulted in their churches."