CLOUDS of noxious gas moved silently through North Craven on Monday night as experts struggled to identify it.

The police received several reports about the foul-smelling fumes but it was not until Tuesday morning that they were tracked to a controlled fire at a farm between Wigglesworth and Long Preston.

The farmer had been burning a combination of contaminated straw, manure and fertiliser, which resulted in a noxious product that baffled officials.

The first report came in at 7.40pm when a woman travelling from Gisburn towards Settle on the A682 drove through what she thought was fog. It was only when both she and her passenger began to feel unwell that she realised it was something more.

A similar story was told by a motorist who smelt chemicals in the 'fog' as she drove on the A65 through Hellifield, and subsequently suffered breathing difficulties.

By 3.40am patchy clouds of the gas had reached Settle and one police officer reported that his throat had been irritated by it.

In the meantime, the fire brigade, water board and DEFRA were all contacted and freight movements were checked to ascertain whether any chemicals were being transported.

The A65 and the A682 were also searched, and it was thought at one point that local people should be warned to stay in their houses and that schools should remain closed.

A spokesman for the North Yorkshire fire service said: "We mobilised units from Skipton and Settle and a salvage unit from Harrogate at 7.45pm after reports of a cloud of what looked like mist was reported, which had a strong and disgusting smell.

"After checks had been made of the area the units retired at about 11pm. The following morning they attended again and the gas was traced back to a farm nearby. The farmer's fire was still smouldering and was properly extinguished."