North York Moors farmers were today "sitting on the edge of a cliff" as foot and mouth disease threatened to explode among livestock.

There was little relief among farmers despite no new cases being reported in the Moors yesterday.

But there were concerns that measures taken to keep the disease out were inadequate as it emerged that foot and mouth may have been brought to the area by a vehicle.

NFU North Yorkshire branch chairman Derek Watson said the moors strain of the disease had an incubation period of about ten days. "The next ten days will be critical and it is like we are sitting on the edge of a cliff."

George Winn Darley, owner of Spaunton Moor, which is near infected areas of farmland, said he had been told by a Government official that they believed the weekend's outbreaks at Westerdale were most likely introduced to the farm on a carrier vehicle.

Charles Scott, Ryedale District councillor for Rosedale, Farndale and Bransdale, said the disinfectant mats put down in the National Park at the beginning of the national outbreak had not been maintained.

He said that the county council had handed responsibility for putting down new disinfectant to the NFU, but that the mats had been neglected, and demanded that MAFF - now the Department for Environment, Food and Rural Affairs (DEFRA) - take responsibility.

The cases at Westerdale were at Waites House Farm, which was confirmed on Friday night, and High House Farm, confirmed on Sunday night.

Updated: 11:11 Tuesday, June 12, 2001