Parishioners who spent 10 years raising £20,000 to build an extension to their village church have learned they must now use the money to pay for the reburial of 120 medieval skeletons discovered in the footings.

St Peter and Paul’s Church in Alconbury, which dates back to the 13th century, is having to foot the bill for an archaeological dig and the re-interment of the remains, which are mostly women and children and may date back to the Norman or even Saxon era.

The grisly discovery came to light when builders began digging the footings for the church’s new porch and community room on the north side of the churchyard.

The building work is the realisation of a 10-year fundraising campaign, called Project 21, that included hundreds of fund-raising events and thousands of pounds in donations.

The Rev Mary Jepp, who joined the church as vicar four years ago, said the news had been a huge blow to her congregation and meant the work could not go ahead unless more funding is found.

“The whole community has been involved in trying to get this project off the ground and I don’t think it is any exaggeration to say that people are heartbroken,” she said.

“This was more than a building project for the church; it was about breaking down barriers in the community and the community coming together. At the moment we just can’t see a way forward.

“There are so many bones – 120 full skeletons - and each one has to be exhumed and then re-interred.”

Along with the bones, archaeologists from the Cambridge Archaeological Unit, in Downing Street, have discovered medieval pottery, coins and shroud pins.

A team of four people have been working on site for several weeks and will produce a report detailing their findings at the end of the month.