TRANSPORT union RMT joined with MPs yesterday to demand a public inquiry into bus companies profiting by refusing to pass oil price cuts on to passengers.

Those in the spotlight include Britain’s five largest operators — Arriva, First Group, Govia, National Express and Stagecoach.

Over the past year oil prices dropped by up to 50 per cent but, rather than falling, fares actually increased by an average 4.8 per cent last year.

The union said it was concerned that operators were “using the fall in oil prices to maximize their profits at the expense of passengers.”

Labour MP Ian Lavery raised questions on the scandal in the House of Commons, eliciting a government ­statement saying: “The Chief Secretary to the Treasury recently wrote to the five largest UK bus operators seeking their assurance that they are doing all they can to ensure passengers benefit from the fall in oil prices.”

But RMT general secretary Mick Cash hit back, insisting that the case for proper scrutiny of bus firms’ reaction to oil prices was overwhelming.

“There has to be an open and transparent inquiry into our clear concerns that bus companies may be profiteering from the fall in oil prices while at the same time they continue to threaten the jobs, pay and working conditions of their staff,” he said.

“If our bus services came under public ownership, rather than the current fragmented system driven purely by profit, it would be easier for the windfall bonus from lower oil prices to be immediately reinvested in services and lower fares.