A BUILDING firm has been ordered to stop its work at a former tip site after pollution left dozens of fish dead.

The fish were discovered in the River Foss, near Yearsley Bridge, in York, on Tuesday and the Environment Agency has launched an investigation.

City of York Council claims there could be a connection between the pollution and work by Harrison Construction on a building site at Birch Park, further up the river.

Officers have written to the company asking it to stop work after discovering what they believed was an "unauthorised engineering operation" designed to tidy up the site in preparation for building - a claim denied by the company.

The council says no planning application has been received relating to the site and that it is on the site of a former waste tip.

Environmental protection officers visited the site yesterday to find out if the tip had been disturbed.

But a spokesman for Harrison Construction said: "The site has not been used for several years.

"All we are doing is simply stripping the grass in order for us to do a level survey prior to submitting a planning application for the site.

"We stand firmly by our view that what we are doing in no way constitutes engineering work. Harrisons has now completed the work and moved off site."