Cecilia Malmstrom
European Trade Commissioner-designate Cecilia Malmstrom said a Brexit would be a disasterReuters

The UK's withdrawal from the European Union would be a "disaster," according to a European commissioner.

Cecilia Malmstrom, who runs the EU's trade portfolio, said a Brexit would hurt the whole continent.

When asked if the UK leaving the EU would be a disaster, she replied: "Yes. For us and for you," the BBC reported.

Malmstrom's stark assessment of the impact of a Brexit marks a shift in the EU's approach, if not its overall position, on the prospect of the UK leaving the bloc. Brussels usually says these kinds of matters should be left for the British people to decide.

The UK's Conservative party has vowed to hold an in-out referendum on the UK's membership of the EU if it wins a majority at the upcoming general election.

The vote would take place after David Cameron has attempted to renegotiate the UK's relationship with the EU, assuming he is still the prime minister.

Cameron has pledged to negotiate a better deal for the UK in Europe, saying he "will not take no for an answer" and "get what Britain needs" regarding freedom of movement restrictions.

British Chambers of Commerce (BCC,) a UK business group, has called for a UK referendum as soon as possible, saying it would reduce the damaging impact of uncertainty.

"If we are going to have a referendum we ought to do it quickly," BCC chief John Longworth said last week, adding that "uncertainty is bad for business."