Lead thieves have attacked five parish churches in the East Riding in the last ten days.
The Diocese of York said "serious damage" has been inflicted on St Peter’s Langtoft, St Mary’s Lockington and St Peter's Wawne, where large areas of lead have been stolen.
St Lawrence at Sigglesthorne has also been targeted and an attempt was made to steal lead from the roof at St Peter’s Hutton Cranswick.
The thieves have been encouraged by a recent sharp increase in scrap metal values on world markets.
Because the roof is usually out of sight, the first sign of damage is water leaking through, damaging historic structures, fabric and artwork.
Community Inspector Phil Hinch, from Humberside Police, said they were also investigating the theft of lead from the roof of a bank in Driffield, which was reported on September 9.
He said: “It is particularly disheartening to hear of people targeting churches as the impact on the local village communities is huge.
“I would appeal for anyone who has any information about these recent thefts to contact us so that we can identify those responsible and bring them to justice.
Diocesan Church Buildings Adviser Keith Halliday said: “This is a national problem for the whole Church of England, and we’re working closely with the police and with local churches to support measures to protect churches from these attacks.
“Whether you’re a churchgoer or not, these buildings belong to their community and they’re a living record of the place they serve.
“Everyone is hurt by these thefts, and in the end the best protection against them is vigilance by everyone in the parish.”