Media playback is unsupported on your device Media caption Steve Messham: "I was absolutely mortified, I really did feel for the man."

A victim of sexual abuse while he was a resident of a north Wales care home has apologised for making false allegations against a Conservative politician.

Steve Messham said police had shown him a picture of his abuser but incorrectly told him the man was Lord McAlpine.

The BBC's Newsnight reported his claims against a leading 1980s Tory politician but did not name Lord McAlpine.

The BBC apologised "unreservedly" for airing it and announced an "immediate pause" in Newsnight investigations.

Meanwhile, Lord McAlpine's solicitor says he will take legal action against those who later named and linked him to the claims.

Mr Messham has offered "sincere and humble apologies" to the peer and his family.

In a statement on Friday evening Mr Messham said: "After seeing a picture in the past hour of the individual concerned, this [is] not the person I identified by photograph presented to me by the police in the early 1990s, who told me the man in the photograph was Lord McAlpine."

He later told BBC News he was "actually mortified" when he realised.

He said recent coverage of the scandal had "brought everything back to the fore but I just want justice for everybody and hope we get justice for everybody".

"But I certainly don't want the wrong people accused, that is also wrong.

"That's why I'm speaking out now and I hope people believe what I say. I am sincerely sorry."

The BBC said that, on Friday night, director general George Entwistle had ordered the following actions:

Sending in a senior news executive to "supervise" Friday night's edition of Newsnight

An apology on Friday's programme

An "immediate pause in all Newsnight investigations to assess editorial robustness and supervision"

Commissioning BBC Scotland director Ken MacQuarrie to write an "urgent report for the DG covering what happened on this Newsnight investigation"

An "immediate suspension" of all co-productions with the Bureau of Investigative Journalism which Newsnight worked with on the programme

"Mr Messham has tonight made a statement that makes clear he wrongly identified his abuser and has apologised," the corporation said in a statement.

"We also apologise unreservedly for having broadcast this report."

North Wales Police, meanwhile, said it would be inappropriate to comment on Mr Messham's allegations about the mix-up over identifying the picture "because an investigation is ongoing".

'Seriously defamatory'

Conservative MP Rob Wilson has written to the chairman of the BBC Trust, Lord Patten, asking him to explain what steps were taken to establish the identity of the man Mr Messham said he was abused by.

Earlier Lord McAlpine's solicitor, Andrew Reid, said the peer had "no choice" but to take legal action over claims linking him to abuse at Bryn Estyn children's home in Wrexham.

Media playback is unsupported on your device Media caption Lord McAlpine's solicitor Andrew Reid: "We have to look at Newsnight and the way in which they behaved"

Mr Reid said the claims were "false and seriously defamatory" to Lord McAlpine, who was Conservative Party treasurer from the late 1970s until 1990.

The solicitor also criticised the way Newsnight aired Mr Messham's claims last week.

Mr Messham, a former resident of the Bryn Estyn home, last week told Newsnight he had been abused by a senior politician of the Thatcher era.

He called for a new investigation claiming a report by Sir Ronald Waterhouse in 2000 had not uncovered the full scale of the abuse.

A BBC spokeswoman said: "Newsnight broadcast an investigation into alleged failures in a child abuse inquiry. It worked with the Bureau of Investigative Journalism to give a voice to concerns raised by an abuse victim.

"It was in the public interest to air these. We did not name any public figure for legal reasons."

In a statement, also on Friday, Lord McAlpine said he had been subsequently named on the internet and by implication by other media over the claims and he was issuing a denial "to set the record straight".

Lord McAlpine said he wanted to "tackle these slurs".

Lord McAlpine Image copyright PA Image caption Lord McAlpine - pictured here in 1998 - now lives in Italy The grandson of construction magnate Sir Robert McAlpine

Married three times, with three children

Made director of family firm at 21

Built up own fortune in property speculation in Australia

Close friend and supporter of Lady Thatcher, who made him a life peer in 1984

Author of several books on art collecting and politics

Appointed Conservative Party Treasurer in late 1970s, holding post until 1990

Deputy chairman of the Conservatives between 1979 and 1983

Backed Eurosceptic Referendum Party ahead of 1997 general election

Has not sat in Lords since rules on non-domiciled tax changed in 2010

He said: "I did not sexually abuse Mr Messham or any other residents of the children's home in Wrexham."

Lord McAlpine, whose grandfather founded the McAlpine construction firm, is a life peer who took the title of Baron McAlpine of West Green in Hampshire.

He became Conservative Party Treasurer in the late 1970s and held the post until 1990. He now lives in Italy.

Lord McAlpine said: "I do not suggest that Mr Messham is malicious in making the allegations of sexual abuse about me.

"If he does think I am the man who abused him all those years ago I can only suggest that he is mistaken and that he has identified the wrong person."

On Tuesday the Home Secretary Theresa May announced a new police inquiry into the allegations of child abuse in north Wales in the 1970s and 1980s.

Mrs May said the head of the National Crime Agency would lead the inquiry.

Separately Mrs Justice Macur will investigate the terms of the Waterhouse abuse inquiry, which began in 1996.

The Home Office said there would be no change to the inquiries announced by Mrs May, following the statements by Mr Messham and Lord McAlpine.

'Disaster'

A number of historical sex abuse allegations have emerged since 3 October, when ITV broadcast a programme which made allegations about former BBC DJ and TV presenter Jimmy Savile.

Police believe Jimmy Savile, who died a year ago aged 84, could have abused as many as 300 people over a 40-year period.

Newsnight is already the subject of a BBC inquiry, headed by ex-Sky News boss Nick Pollard, into why the programme dropped an investigation into sexual abuse claims against Savile last year.

Media playback is unsupported on your device Media caption Media commentator Steve Hewlett: "This is a disaster for the BBC"

Media commentator Steve Hewlett said: "For the BBC this is just a disaster. You have a programme like Newsnight which in the last few weeks has been flayed alive for not broadcasting something that probably was true (about Jimmy Savile) and has now responded - or that's how it appears - by broadcasting something that flagrantly wasn't true.

"How on earth did it get on air? If there are questions about the BBC these just multiply them. What does this say about the BBC's journalistic standards? It looks like it was done on the rebound."

He said there were also questions for the government, who decided to order a new inquiry: "The problem with calling a new inquiry is that where is the new evidence. If the grounds (for calling a new inquiry) had anything to do with what was broadcast on Newsnight then we've all been sold a pup."