Talks aimed at averting a strike planned for tomorrow by hundreds of tanker drivers continued last night amid signs of motorists panic-buying petrol.

Leaders of the Unite union were meeting officials of two companies working on Shell delivery contracts in a bid to resolve a row over pay, but were struggling to find a resolution.

The government repeated its request to motorists not to panic-buy as queues started at some garages. "We want the public to continue to buy as normal so as to avoid creating problems that might otherwise not exist," said a Downing Street spokesman.

Contingency plans include maintaining fuel supplies to the emergency services. Tony Hayward, the chief executive of BP, said his company was implementing a "well-rehearsed" programme to try to minimise the impact of any strike at Shell garages, which make up one in 10 of all stations.

The tanker drivers claim they are paid the same now as they were in 1992, just under £32,000 a year, despite working 11 more hours a week.

Bernie Holloway, spokesman for Hoyer, the biggest of the two transport companies involved in the dispute, said it was "disappointing" that Unite had rejected an improved pay offer last week.

"We believe this was a very good offer that would take the average driver's pay up to around £39,000," he said. The company said its improved offer was worth 6.8%.

Unite repeated its call for Shell to get involved in the dispute. "It is no use Shell bosses, who have themselves enjoyed 15%-plus pay increases in the last year, sitting on their hands," said Unite's assistant general secretary, Len McCluskey.