Liberal Democrat leader Tim Farron has accused the Labour Party of acting as an "accomplice" to the Conservatives in pushing through a hard Brexit.

Opening the Lib Dems spring conference in York, Mr Farron branded Jeremy Corbyn the "worst opposition leader in British history" and said Labour was incapable of holding the Government to account.

"They are no longer content with merely not being fit for government, they are determined to prove they are not fit for opposition either," he said.

"The worst opposition leader in British history. The man who makes IDS look like JFK. Labour is not an opposition, Labour is an accomplice."

His speech will be seen as a renewed attempt by the Lib Dems to pick up votes from Labour Remain supporters disillusioned with what was seen as Mr Corbyn's tepid performance in last year's referendum campaign.

At the end of a week in which Mr Corbyn was again criticised for failing to exploit the Government's Budget U-turn over National Insurance, Mr Farron openly mocked the Labour leader.

"There was some controversy when Jeremy Corbyn forgot, on his tax submission, to declare his opposition leader's salary," he said.

"But I don't think there was any foul play there. It was an honest mistake. I think he genuinely forgot that he was Leader of the Opposition."

Mr Farron said the Lib Dems would continue to resist Theresa May's plans for a "hard Brexit", leaving the single market and the European customs union.

"Don't buy this guff that they are enacting the will of the people. They are distorting the will of the people either by design or through utter weakness," he said.

"Who says that the will of the people is a hard Brexit, out of the single market, out of the customs union, into the pit of protectionism?

"Well, we will not roll over, we will not give up."

A Labour Party spokesman said: "The Lib Dems should be careful of reminding us about 'accomplices'. After all, they're the ones who enabled the Tories in government.

"Their support allowed the Tories to cut public services, hammer the NHS, leave working people worse off and treble the tuition fees they'd promised to cut."