Everton's plans to build a new 50,000-seater stadium have been jeopardised by a colony of water voles.

The Merseyside club want to move from their present Goodison Park home to a state-of-the-art arena in Kirkby, a northern suburb of Liverpool, but the protected species has been discovered on the prospective construction site.

The rodents live on the banks of Kirkby Brook, which crosses the site, and must be moved before building work can take place.

Developers must complete the relocation before autumn, when the animals hibernate, as it is illegal to disturb a sleeping vole.

A spokesman for Knowsley council, which has backed the move, said: "As landowners, we have granted a licence for our land to be accessed in order for ecological works to be undertaken.

"These works will ensure the safe translocation of a protected water vole habitat in Kirkby Brook.

"The work will include the erection of safety hoardings, systematic clearing of overgrown vegetation and vole assessment."

Everton's Kirkby project is still awaiting final approval pending a public inquiry, the outcome of which is expected by November. If the stadium gets the green light, the Toffees will move there in 2012.