The news of Mr Hague's tour follows the launch of the Britain in Europe campaign, which saw senior Tories join the prime minister on a pro-European platform.

Mr Hague will deliver the message "vote Conservative to save the pound" from the back of a lorry emblazoned with the slogan: "Battle for the Pound, Battle for Britain."

Mr Hague said: "Mr Blair has finally, if half-heartedly, joined the debate on the single currency.

"But he is wrong if he hopes that this issue will now just fade away."

Mr Hague added: "For from today I will be leading a full-blooded campaign - the Battle for the Pound, the Battle for Britain."

BBC Political Correspondent John Pienaar: "This could once again make William Hague an easy target"

The tour is in response to the pro-European alliance between Tony Blair and senior Tory ministers Kenneth Clarke and Michael Heseltine, as well as Liberal Democrat leader Charles Kennedy, at Thursday's Britain in Europe meeting.

The campaign, which has been called the most powerful pro-European alliance Britain has seen in 20 years, boasts the greatest cross-party support on European issues since the referendum of 1975.

The former Conservative chancellor and deputy prime minister denied any disloyalty to their party in taking part in the campaign.

But the Tories have accused the BiE campaign of being a front for Britain joining the single currency without openly stating its intention.

Mr Blair said he was making the case for the UK being in Europe to rebut a growing "chauvinistic" and "isolationist" anti-European clamour.

The prime minister said backing a UK committed to the future of the European Union was a "patriotic" cause.

He said: "I am proud to be part of a gathering that stretches across all political parties and none to make our case for Britain in Europe to our country.

"In 1975 I voted Yes in the referendum. I believed Britain's destiny was in Europe then and I believe it now."

The prime minister said that EU membership is not just an "adjunct" to the British economy.

Kenneth Clarke: "This is an all-party occasion"

"To quit Europe would be an act of economic mutilation," he said.

Mr Heseltine said he and Mr Clarke had joined the campaign because "all our lives we have shared that same belief in a combination of practical, national self-interest with political vision which has guided our party for half a century".

Leaning together: Ken Clarke and Gordon Brown

Mr Clarke implicitly condemned Mr Hague's policy of ruling out scrapping the pound for the whole of the next Parliament.

He told the meeting: "We've got to be ready to join the single currency, not at some artificial date in the future, set quite arbitrarily for some reason, but at the pace which events determine."

The Britain in Europe meeting aimed to highlight the importance of the UK's membership of the European Union.

It was also meant to highlight the potential benefits of a successful euro - although due to internal wrangling it did not declare full backing for the single currency.

(For an interactive guide to politicians' views on the euro click here)

But anti-euro pressure group Business for Sterling used documents filed by Britain in Europe at Companies House earlier this year to claim its secret agenda was joining the single currency.

The group registered its objectives as campaigning "in favour of UK membership of the single currency".

Business for Sterling chief executive Nick Herbert said: "Britain in Europe are lying about their real agenda.

"They dare not admit they are the pro-euro campaign."

Conservative Europe spokesman Archie Norman described Mr Blair's speech as "another example of Labour's remarkable deceit over their commitment to scrap the pound and join the euro".