The Treasury has announced that the tax reduction on ultra-low sulphur petrol (ULSP), signalled by Gordon Brown last November and expected to be around two pence per litre, will be matched by a temporary cut in unleaded petrol duty.

Following meetings between ministers, representatives of the major oil companies and independent petrol retailers on Wednesday, Stephen Timms, the financial secretary, announced that "the government intends to match any reduction in duty on ULSP that is announced in the Budget with a reduction in duty on unleaded petrol for a temporary period until 14 June 2001".

Ministers have decided a temporary reduction is necessary because constraints on the capacity of UK oil refineries may delay the transition by independent retailers to ULSP. In comparison, the big oil companies are on track to supply ULSP nationwide by the end of March.

Timms said the move would "guarantee that all motorists would benefit from a cut in duty on Budget day".

Lib Dem spokesman Don Foster said: "This cut is plainly a pre-election stunt. It is a bribe to pacify motorists."

The announcement comes as petrol tax protestors across Wales and England prepare to launch the first of their "public awareness days" on February 24.