Image caption Warren Blackwell served more than three years in prison

A man who spent more than three years in jail for a crime he did not commit has described an apology from the police as "too little, too late".

Warren Blackwell was convicted in 1999 of sexual assault, but in 2006 new evidence undermined the credibility of the woman who made the allegation.

The Independent Police Complaints Commission has criticised the handling of the case by Northamptonshire Police.

Deputy Chief Constable Derek Talbot said he has apologised to Mr Blackwell.

Possible damages claim

He added: "Northamptonshire Police acknowledges and regrets that some aspects of the investigation and handling of information, which emerged after Mr Blackwell's conviction in 1999, fell well below the required standard."

Mr Blackwell was jailed in October 1999 and was released in February 2003. His conviction was quashed more than three years later, in September 2006.

Mr Blackwell, 40, from Woodford Halse, said the apology was "too little, too late.

"At the end of the day it was just a token gesture," he said.

"Life goes on. I almost stepped back into work straight away, you've got to get on with these things.

"It's been frustrating the length of time it has taken to draw a line under it and I don't think I'm quite there yet."

He added that the report is "damning" and that he was taking legal advice on whether or not to bring a damages claim against the force.

The Independent Police Complaints Commission said the force failed to disclose concerns expressed by an officer from another force about the alleged victim's reliability.

Notes taken by the Northamptonshire detective referred to her as "unreliable" and "unstable", but there was no evidence to show this information was ever passed to senior officers or the Crown Prosecution Service (CPS).

While Mr Blackwell was in prison, a detective failed to make senior officers and the CPS aware of more information about false complaints by the same woman with striking similarities to Mr Blackwell's case, the IPCC said.

Timeline of Mr Blackwell's case 1 January 1999: Complainant says she was attacked outside social club

October 1999: Warren Blackwell is convicted

March 2002: Court of Appeal denies Mr Blackwell leave to appeal and increases his sentence from three to five years

June 2004: Criminal Cases Review Commission asks West Midlands Police to assist in a review of the case

September 2006: Mr Blackwell is cleared by the Court of Appeal

June 2010: IPCC publishes its findings in respect of complaints against Northamptonshire Police made by Mr Blackwell and strongly criticises the force

There were also a large number of serious discrepancies in her accounts which seemed not to have been challenged by detectives.

IPCC Commissioner Amerdeep Somal said: "As the Court of Appeal has ruled, Warren Blackwell was subject to a terrible miscarriage of justice.

"Nothing can bring back the three years four months he wrongly spent in prison.

She added: "I am dismayed that Northamptonshire Police has taken so long to issue an apology to Mr Blackwell that he has patently deserved."

Ms Somal also expressed her "deep dissatisfaction" with the "unacceptable" length of time the force had taken to resolve disciplinary matters.

The IPCC probe found failings by three officers who had a case to answer on misconduct grounds.

But the CPS proposed no criminal action should be taken, the IPCC said.

One officer has retired and two others will now receive "management words of advice".

The woman who made the false allegations was named in the House of Lords in 2006 by Labour peer Lord Campbell-Savours, during exchanges about the rape laws.