THE clean-up operation at a York stream continues as it emerged that fuel thieves could be behind a pollution incident.

Up to a dozen Environment Agency and RSPCA officials have been busy clearing Osbaldwick Beck after a suspected red diesel oil leak.

Since the incident was reported on Tuesday pollution-busting booms have been placed in the water, with attention focused on the Hull Road Park area.

Peter Stevenson, of the agency, said a possible cause was fuel thieves. They may have drained diesel from a vehicle upstream, before leaving a tank open and causing the spill.

The environmental manager added: "We're not certain, but that's a possible cause. We may never find out."

Plans to bring in a tanker were today ditched because not enough oil was soaked up.

"We've put a couple more booms in and will take away oil that has been soaked up.

"Hopefully today's work will clear up the majority of it. But we'll continue monitoring the situation."

The source of the leak in the Murton area had not yet been traced, so the amount leaked could not be confirmed.

Hundreds of ducks may have been caught up in the spill..

RSPCA workers caught seven ducks and sent them to a York vet to be cleaned, as reported in yesterday's Evening Press.

The agency stressed the leak was not a danger to drinking water supplies and said environmental damage was not serious.

A Millfield Avenue resident living near the beck said: "Last night there was a real reek of diesel. You can still smell it today."

Updated: 09:39 Saturday, December 20, 2003