His decision comes after days of mounting pressure during which he has consistently denied the accusations made against him.

In an emotional speech to assembly members, Mr Buhari said: "I apologise to you. I apologise to the nation. I apologise to my family and friends for all the distress I have caused them.

"I was misled in error by zeal to serve the nation," Mr Buhari said.

"I hope the nation will forgive me and give me the opportunity to serve again."

Humiliation

The BBC correspondent in Nigeria, Barnaby Phillips said the statement amounted to a humiliating climbdown for Mr Buhari, who has until now vehemently denied allegations that he lied about his age and educational achievements in order to qualify for the post.

On Tuesday, the speaker said he would step down "temporarily" to fight the allegations made in The News magazine.

The magazine has stood by its story despite Mr Buhari's threat to sue for libel.

The News said that Mr Buhari is seven years younger than he claims to be, making him too young to enter the House.

It also said that Mr Buhari did not go to the university in Canada which he says he attended.

'Never resign'

On Monday, the speaker held a press conference saying he would "never resign."

The announcement of his departure was made to a session of the House of Representatives by acting Speaker Chibudom Nwuche.

Mr Buhari's replacement as speaker will be Ghali Umar Na'aba, a 41-year-old graduate of political science from Ahmadu Bello University, Zaria.

The speaker of the house is key post in Nigeria's fledgling democracy, and fourth in the country's constitutional hierarchy after President Obasanjo, the vice-president and the speaker of the senate.

Mr Buhari had faced growing calls for his resignation over the past few days and there were reports that his own party - the People's Democratic Party - was urging him to quit.

On Tuesday, tempers flared in the House of Representatives, and proceedings were suspended as members opposed to Mr Buhari attempted to seize the ceremonial mace to prevent a motion in support of the speaker going ahead.