Jimmy Johnson, 72, believes a drain pipe is carrying rainwater into the moat, leaving large pools of water, and he fears youngsters, who play nearby, could sink into the soft ground.

Mr Johnson, of Tuthill, said: "When it rains it gets really bad and recently there were huge pools of water. I walk there every day with my dog Misty and it is getting worse and worse.

"The pipe is just bringing the water down the hill and into the moat. It needs to be linked to the drainage system, but at the moment the water is just coming out and causing it to flood.

"The pipe used to be blocked, meaning water could not flow through it. However it was recently unblocked by the council which he said started the problem. English Heritage, which runs the castle, said it was not to blame for the problem.

A spokesman said: "The drains are at Castlegate and are therefore nothing to do with English Heritage. There is a bit of flooding there but it is not caused by the castle, which is open as normal."

Mr Johnson, who has reported the problem to the council, said: "Something definitely needs to be done. It will just get worse when it rains again.It needs to be blocked so the water cannot come out. I think it is very dangerous."

A spokesman for Scarborough Council said: "We have looked at the area and no action will be taken. The moat is meant to hold the surface water that comes from the footway gullies. That is what it is there for.

"The water will then dry up in time."