He set forth his strongest attack yet on Tony Blair in his party conference address, which comes mid-way through the electoral cycle with the opposition still trailing in the polls.

Mr Hague's speech also represented the fiercest attack on Europe and the single currency made by any Tory leader.

BBC Chief Political Editor Robin Oakley: Party managers will be watching the opinion polls anxiously for impact of speech

He told the party faithful in Blackpool the case for the euro was "entirely unconvincing".

Mr Hague said: "When we're in government the next new EU treaty must contain a flexibility clause or else I tell you there will be no new treaty."

'Labour lies'

The Tory leader branded the prime minister a liar and said he could not be trusted to keep his promises.

The "great Labour lie" had been to present New Labour as a party based on Thatcherite ideas ahead of the 1997 election, Mr Hague said.

Within that "great deception" lay layers of further unfulfilled promises.

"When Tony Blair told the country he'd 'no plans to increase tax at all' was he telling the truth?

"Or when he wrote to anxious parents: 'A Labour government will not close your grammar schools - that is my personal guarantee', was he telling the truth?

"When Tony Blair wrote in The Sun newspaper before the election about 'my love for the pound' and how he felt so emotional about the Queen's head on a £10 note, was he telling the truth?

"When can you be absolutely 100% cast-iron sure that a Labour promise is going to be broken?

"The moment Tony Blair puts it in his own handwriting."

Tony Blair: The Tory leader called the prime minister a "liar"

A Downing Street spokesman said the prime minister's office had no immediate plans to respond to the attack.

But the Conservative leader seized on different accounts the prime minister had in the past given to interviewers about his favourite food to hammer home his point.

"According to Labour's own magazine, 'Tony's favourite food is fish and chips. He gets a takeaway whenever he is at home in his constituency.'

"But when The Islington Cook Book asked him the same question he said his favourite food was 'fresh fettuccini garnished with an exotic sauce of olive oil, sun-dried tomatoes and capers'."

'Britain needs common sense'

Mr Hague told his party they could fight back against the "Labour lies" by championing the beliefs of the majority of British people.

He insisted ordinary voters would have been appalled to hear Mr Blair describe Conservatives as extreme during his conference speech last week.

William Hague's speech ended the Tory conference

"I've got news for Tony Blair. These people are not extreme. They're not fanatics. They've got more sense in their gut instincts than in all the collective wisdom of this government and their fellow travellers."

The speech came at the end of the Conservative conference, which has seen the party unveil its "Common Sense Revolution" policy document.

"When the government of Britain is the most two-faced, interfering, over-regulating, bossy, intolerant, arrogant and crony-run in our history, there is no doubt Britain needs a common sense revolution," Mr Hague said.

He said it would be truly revolutionary to bring down taxes, offer hospital patients guaranteed waiting times and let schools take over their management from Local Education Authorities.

But he has struggled at times during the week to make his ideas heard above the blare from the party's former "big beasts".