First said without them it can lighten trains so they travel more quickly.

But the Rail Maritime and Transport (RMT) union warned the move could lead to a loss of jobs.

"Of all the things that hold up First Great Western trains buffet cars are the least of their concerns," said Alex Gordon of the RMT.

"We've heard about points failures, about leaves on the line, signal failures and broken trains but really blaming it on the sandwiches just takes the biscuit," he added.

First said it would bring in trolley services to replace buffet cars.

The move would also help it make a saving of some £40,000 a year in leasing costs.

In a statement the company said: "The RMT is scaremongering. There will be no job losses and trains on long distance services at busy times will not be affected."