But they insist that the present playing surface will be in a condition capable of hosting next month's CIS Insurance Cup semi-finals.

BBC Scotland disclosed last month that the �800,000 undersoil heating system had been punctured.

Leaking pipes left a layer of ice on the pitch and now stadium director David Kells has admitted that it could have been caused by a forking machine used by the two full-time groundsmen.

"There are leaks in the system. It may be down to some equipment that's been used on the park.

"The pipes are 10 inches below the surface, so there is the possibility that something has pierced some of the pipes."

The national stadium is due to host the showpiece matches between Celtic and Rangers and Ayr United and Hibernian.

Hampden's bosses will now use an inflatable, heated dome to protect the pitch for those showpiece games.