Charles Kennedy yesterday struggled to explain one of the Liberal Democrats' flagship tax policies as he unveiled the party's manifesto.

Launching the 20-page document, titled The Real Alternative, he underlined the party's promise to introduce a 50p top income tax rate for the one per cent of people earning more than £100,000 a year, and to replace council tax with a "fairer" local income tax.

But he was unable to explain details of how the tax would work, allowing the Tories to brand the Lib Dems "a shambles".

A senior Lib Dem judged Kennedy's comments "irritatingly wrong".

Liam Fox, the Tory co-chairman, said the tax plans were in disarray.

"People will look at the Liberal Democrats this morning and see what a shambles they are," he said.

"They do not even know the details of their own tax proposals."

The Lib Dem leader also highlighted the party's commitments to scrap personal care charges for the elderly, axe tuition fees, and add £100 a month to the pensions of those over 75.

Kennedy promised the Lib Dems would fund 21,000 extra teachers and 10,000 more police officers.