Stephen Byers has said that Brussels must do more to combat its "out of touch" image if the prime minister is to win his referendum on the new European Union constitution.

The former Cabinet minister, a pro-European and close ally of Tony Blair, warned on Saturday that without reform the British public could reject the recently agreed deal.

Speaking at a conference in the Ukraine, Byers warned Brussels chiefs that they were seen as "bureaucratic, intrusive, inefficient and out of touch".

"To be in with a chance of winning the referendum in the UK, Brussels must change," he said.

"It needs to be in touch with what people want and reflect their priorities."

Byers also warned that the recent European parliament elections, at which the UK Independence Party made dramatic gains, showed that euroscepticism was on the rise.

And he said that the Commission's procedures and priorities made it a "soft target".

But there was also a warning to ministers that they must go out and make the pro-European case to the British public.

"The lesson of the last few years is clear," he said. "You cannot win an argument over Europe unless you go out and make it."

A campaign in favour of the EU was also needed to show that the European project us "not a conspiracy against the British people".