Conciliation service Acas has invited unions and oil companies to talks in a bid to prevent a tanker drivers' strike over Easter.

Workers in five of seven companies involved in the row over terms and conditions and safety standards have voted in favour of strikes, raising the threat of walkouts over the Easter weekend, when millions of families will take to the road for the first major holiday of the year.

Energy Secretary Ed Davey has written to Unite asking the union to get round the table with the haulage companies, and suggesting the use of the resolution body.

The Energy Secretary also asked Acas to approach both parties to try to achieve a "negotiated settlement".

An Acas spokesman said: "We welcome the minister's suggestion about the parties responding positively to an invitation to come in to Acas.

"We are establishing contact with all the parties involved in this dispute and will be looking to see whether we can enable an Acas process to allow the possibility of some form of dialogue to start.

"Of course, take-up of Acas conciliation is voluntary and the parties themselves will determine whether they wish to respond positively to our invitation."

Downing Street has urged unions and oil companies to hold talks to prevent a strike, as senior ministers met to draw up contingency plans to keep vital services moving.

Prime Minister David Cameron and his Cabinet were briefed on plans to put military personnel through an eight-day training course to take the place of striking drivers behind the wheel of commercial tankers, although Downing Street said the training had not yet started.

Cabinet Office minister Francis Maude said the Government had "learnt the lessons" of the previous disruption to petrol supplies in 2000, when pumps ran dry around the country, and was putting plans in place to keep Britain moving, but acknowledged that there was still "more work to be done".

Labour leader Ed Miliband said a strike should be avoided "at all costs" and urged union and company chiefs to get round the table and negotiate.

Unite - which represents around 2,000 drivers who deliver fuel to Shell and Esso garages as well as supermarkets such as Tesco and Sainsbury's, covering 90% of the UK's forecourts - wrote to Mr Davey setting out its case for minimum standards in the industry, covering pay, hours, holiday and redundancy arrangements.

Assistant general secretary Diana Holland said in her letter: "We have been tireless in seeking talks to avoid industrial action, but we have been frustrated at every turn.

"The Government can help avoid confrontation by bringing to the table all the stakeholders in the downstream oil distribution sector - employers, oil companies, retailers and the trade union with an agreement to establish minimum standards in a timely fashion."

In his response, Mr Davey stressed that the Government did not intervene in disputes, and said the HSE and Department for Transport believed current health and safety standards were "proportionate", according to aides.

However, ministers were taking Unite's concerns on health and safety "seriously".