Rural churches have been put on the alert to beware of thieves who are stealing large slate slabs from porches and lych gates.

Two recent thefts, one in Bradoc near Liskeard, the other in Boscastle, have led police to warn isolated churches that they may be targeted.

At Bradoc large slate slabs from the porch were taken, and the picturesque St Juliots near Boscastle, a church which is associated with Thomas Hardy, lost its porch slates and a mounting block at the gateway to the graveyard.

All the items taken were very heavy and police say that the thefts must involve at least two men and a van or lorry.

Church spokesman for the Diocese of Truro, Jeremy Dowling said 'These are large Delabole slabs, over an inch deep and of considerable weight.

'In each case they have been removed from isolated churches. We would advise churchwardens and those living near churches to be especially vigilant at present. Any unusual activity particularly involving vans or lorries, which are not local, should be noted and the police informed immediately.

Mr Dowling added that it was felt that the increasing popularity of television programmes designed to makeover gardens, rooms and patio areas had created a new market for slate, particularly in large slab form.

He said that security in recently years had been increased for church interiors resulting in a decline in thefts of valuables but churches may now have to consider outside security devices to prevent this kind of theft occurring .

Mr Dowling said it was the first time westcountry churches had been hit in this way. Elsewhere in the country parochial church councils knew that monuments, urns, troughs and memorials were already in danger. Now slate flooring must be added to the list.

Last year television gardening programmes were blamed for the theft of attractive stones from Cornish beaches, leading to at least one parish council in the county to issue leaflets to holidaymakers, warning of prosecution for beach theft.

Large slates of the kind stolen at Bradoc command a good price, around £150 to £200 per slab.