Peter Mandelson, European trade commissioner, has said the protectionist stances taken by the US presidential candidates risk taking the world trading system back by decades.

In an interview with the BBC’s Hardtalk programme to be broadcast on Thursday, Mr Mandelson said: “It is irresponsible to be pretending to people you can erect new protection, new tariff barriers around your economy in this 21st century global age and still succeed in sustaining peoples’ living standards and jobs. It is a mirage and they know it.”

Mr Mandelson declined to say which candidates he had in mind, but the context made it clear he was referring to Democrats Hillary Clinton and Barack Obama “You match the rhetoric. I am not going to do that.”

Mrs Clinton and Mr Obama’s statements on trade have become increasingly specific. Both senators have supported a bill that would allow the US to impose trade tariffs on China to compensate for what it says is the undervaluation of the Chinese currency, a move which would almost certainly be a violation of World Trade Organisation rules.

Mrs Clinton has also called for a renegotiation of the North America Free Trade Agreement and for a “time-out” on new trade deals until present agreements have been assessed.

Mr Mandelson said that even the rhetoric of protectionism was damaging. “It is very irresponsible in my view to pretend to people that we can disengage from international trade, we can create barriers around our economy and then be surprised when people retaliate by doing the same,” he said. “It is going to lead us into a vicious spiral of beggar-thy-neighbour policies which will take us decades back in terms of trade growth.”

Mr Mandelson has previously said Mrs Clinton’s views on trade were unhelpful, but this interview marks a sharp increase in his criticism of the Democrats.