Former European Union Commissioner Sir Leon Brittan has urged Prime Minister Tony Blair to intervene in what he says is a damaging cabinet split over the single currency.

The appeal followed Foreign Secretary Robin Cook's rejection of reports of a rift between him and Chancellor Gordon Brown over whether the UK should ditch the pound.

Mr Cook denied claims that Mr Brown had "gone off" plans to hold a referendum on joining the new currency after the next general election.

But Sir Leon said that the UK was losing influence in Europe because of the government's indecision over the euro.

"There is no doubt at all there is uncertainty and division, with cabinet ministers taking up contrasting positions in public," he said.

"That means that the apparently clear view of the government that it was giving to foreign governments that they were gradually taking us forward and we would join after the next election is utterly obscured.

"That means we lose influence in Europe and any hope of playing a central and indeed leading role in Europe becomes more and more remote."

The former Tory minister said the five economic tests set down by the government, as preconditions for a referendum on the euro, could be interpreted in any way people wanted.

He added: "If Tony Blair wants to have a leading role in the European Union he will have to personally assert himself amongst his divided cabinet."

Trade Secretary Stephen Byers had already warned that foreign investors were increasingly unlikely to come to Britain because it had not adopted the single currency, he warned.

Sir Leon added: "We ought to be listening to that."

But in an interview with The Spectator magazine, Mr Cook strongly denied that he was at odds with Mr Brown.

"There is no dispute between me and Gordon Brown," he said.

"I don't have a problem with Gordon Brown. It is to trivialise it to say there is a dispute between me and Gordon Brown. For the record, I think he has been a very good chancellor."

In a question about the timing of a referendum Mr Cook quoted a remark by Alastair Campbell, the prime minister's press secretary, that Britain would not be "bounced" into the euro soon after the next election.

Mr Cook said: "It is not a big policy question whether it is year one, or year two or year three. The objective is clear and the timetable is clear. It could be year three. I am not speculating."

Asked why Britain could not join the single currency now, Mr Cook said: "It would be a challenge for us to harmonise interest rates with Europe at the present time."

Mr Cook rejected the idea that he was allowing the pro-euro campaign to atrophy, saying: "I am quite clear that I have put to the people the reasons why it could be in Britain's interests to join the euro."