A reservoir has been closed to the public after several hundred litres of a highly toxic wood preservative seeped into the water.

A small amount of the powerful toxic insecticide permethrin was among the chemicals leaked into Doe Park reservoir, Denholme, just two tablespoons of which is enough to kill all animal life in size of a body of water such as the much bigger Scammonden reservoir by the M62.

The reservoir is not used for drinking water but is home to a range of wildlife and is regularly visited by anglers and sailors and both groups have been advised to avoid the spot.

Investigators believe they know the source of the leak of Protim on Saturday but are not releasing details yet.

None of the animals, including coarse fish, birds and insects, have died so far but the Environment Agency will continue to monitor the situation.

It joined staff from Bradford Council and Yorkshire Water to minimise damage and specialist clean up contractors were called in to deal with the spillage.

Agency officer Nick Reynolds said: "We estimate the Protim contains around 0.1 per cent of permethrin.

"This may seem a small amount, but just two tablespoons of this chemical could, theoretically, wipe out all animal life in a body of water.

"Fortunately, the Protim that leaked into Doe Park had been dissolved in white spirit. This kept it floating on the surface of the water and prevented it from dissolving and spreading.

"The weather was on our side and the wind contained the pollution in a corner of the reservoir. Booms were then used to stop it spreading further and suction equipment is now being used to remove the spill."

A decision on whether to prosecute as a result of the spill has not yet been taken by the agency.