Chris Huhne has resigned as Energy and Climate Change Secretary after being charged with perverting the course of justice over allegations that he asked his ex-wife to take a speeding penalty for him.

Mr Huhne and his former wife, economist Vicky Pryce, who faces the same charge, will appear before Westminster Magistrates' Court on February 16.

The charge - which carries a maximum sentence of life imprisonment - will eventually be heard by a judge at Crown Court.

Speaking at his London home less than an hour after the decision to prosecute was announced, Mr Huhne, 57, said he was quitting David Cameron's Cabinet in order to fight to clear his name. "I am innocent of these charges and I intend to fight this in the courts and I am confident that a jury will agree," he said.

Lib Dem business minister Ed Davey will take over as Energy Secretary following Mr Huhne's resignation, Downing Street has said. Norman Lamb, parliamentary aide to Nick Clegg, has been promoted to Mr Davey's old post as business minister and Cardiff Central MP Jenny Willott becomes assistant whip.

Mr Huhne made clear that he will remain MP for Eastleigh in Hampshire while he awaits trial. "So as to avoid any distraction to either my official duties or my trial defence, I am standing down, resigning, as Energy and Climate Change Secretary," he said.

Mr Huhne is entitled to a severance payment of more than £17,000. Under the 1991 Ministerial and Other Pensions and Salaries Act, the Liberal Democrat is allowed three months'-worth of his £68,827 annual ministerial pay, the Cabinet Office said - entitling Mr Huhne to £17,207, if he chooses to accept it.

In a written response to Mr Huhne's resignation letter, Deputy Prime Minister and Lib Dem leader Nick Clegg said he was "immensely grateful" for the former minister's contribution as Energy Secretary, adding that he "fully understood" the decision to step down in order to "clear his name".

Speaking later, Mr Clegg said if Mr Huhne cleared his name he would "like to see him back in Government in a key position".

In a statement, Ms Pryce, an economist, told the BBC she hoped for a "quick resolution" to the case.