Millions of homeowners are paying a “Conservative property premium” as a result of the “chaos” the party has unleashed on the economy, Liberal Democrat leader Sir Ed Davey has said.

In a keynote speech, Sir Ed said the Government did not have a “shred of credibility” after the turmoil of recent weeks as he reiterated his demands for an immediate general election.

He called for the creation of a £3 billion mortgage protection fund – paid for by reversing cuts to taxes on banks dating back to 2016 – to assist families now facing crippling increases in their repayments.

Under the Lib Dem proposal, homeowners who see their repayments increase by more than 10% of their income would be able apply for grants of up to £300 a month to help cover the costs.

Speaking in London, Sir Ed said homeowners should not have to pay the price for the “mess” created by Liz Truss and Kwarsi Kwarteng’s mini-budget.

“Instead of tackling the cost-of-living crisis seriously, they chose to treat the British economy as their own personal playground – using people as playthings in their reckless game of fantasy economics,” he said.

“Just look at the damage… millions of families struggling to pay a Conservative property penalty, every single month.

“Never again can the Conservatives claim to be the party of homeowners.

“Never again can they claim to be the party of business. Never again can they claim to be the party that balances the books.

“The Conservatives are the party of chaos.”

Sir Ed delivered his autumn speech after the Lib Dems were forced to cancel their annual conference in September due to the period of national mourning following the death of the Queen.

With the Government preparing a package of tax rises and spending cuts to address an estimated £50 billion black hole in the public finances, he said voters are now having to pay to clear up the problems the Tories created.

“After inflicting so much chaos and damage, the Conservatives want the rest of us to pay to clear up their mess. They’re like bank robbers asking for a loan to buy the getaway car,” he added.

Sir Ed said events in Ukraine had only strengthened the Lib Dem argument for the Government to extend the windfall tax on the “record” profits of the oil and gas companies.

“The case for our windfall tax has only got stronger, as those profits have soared even higher for one main reason – a brutal dictator spilling innocent Ukrainian blood,” he said.

“There are no arguments left. The right thing to do – the fair thing to do – is to tax those blood-oil profits.”

Sir Ed said it was “obvious” the country needs a general election and he accused Rishi Sunak of refusing to go to the country because he knew the Conservatives would lose.

In a direct message to the Prime Minister he said: “Your Government does not have a shred of credibility left. It does not have a shred of legitimacy left. If you had a shred of integrity left, you would call a general election now.”