The government urged the public to fill up with petrol on Wednesday ahead of an impending strike by tanker drivers that could see stocks run dry, but was branded irresponsible by petrol retailers who said the government was creating a crisis.

The government, which put the army on standby on Tuesday to help if truckers go ahead with action, told Britons to take sensible steps.

If there's an opportunity to top up your tank if a strike is potentially on the way, then it's a sensible thing if you're able to do that, said Prime Minister David Cameron.

Cabinet Office minister Francis Maude had earlier suggested Britons also keep a little (fuel) in the garage as well, although both he and Cameron said there was no need to rush out to the pumps.

About 2,000 fuel truckers have voted for a strike, according to the Unite union, which has warned the action could hit 90 percent of Britain's petrol forecourts and stocks would begin to run dry within 48 hours of any action.

No dates for any action have yet been set and the union must give seven days' notice before any walkout. Tanker drivers are demanding better terms and conditions.

Brian Madderson, chairman of RMI Petrol which represents petrol station retailers, said the government's message was totally, totally irresponsible, inept. They are making a crisis out of a serious concern, he told Reuters.

Madderson said the suggestion of stockpiling was already leading to some filling stations running out of fuel. He said his members would also need assurances before tankers driven by soldiers would be allowed onto forecourts.

The Fire Brigade Union said the government's advice to fill up petrol jerry cans would increase the risk of fires and explosions.

Cameron described the strike as unjustified and urgent mediation talks were underway to try to find a solution.

We'll do everything we can to prevent it, Cameron told reporters at a briefing about this summer's London Olympic Games.

While the tanker driver dispute is centred on safety concerns and working conditions, it comes against a backdrop of union anger at tough austerity measures to tackle a record peacetime public budget deficit.

Unite's leader Len McCluskey, one of Britain's more militant labour leaders, has already said workers should consider strike action to disrupt the Olympics and Maude accused him of manufacturing the current dispute.

There are people who believe that this is part of Len McCluskey's grand plan to bring the country to a juddering halt, Maude said.

He's already threatened to bring the country to a halt during the Olympics at a time when the eyes are going to be on us. This is part of his plan.

(Additional reporting by Tim Castle and Stephen Addison; Editing by Susan Fenton)