Terror chief quits after being accused of 'inappropriate contact' with a woman police watchdog official

Andy Hayman is said to have exchanged as many as 400 text messages and calls with the civil servant. The woman worked for the Independent Police Complaints Commission while it was compiling its damning report into the death of Jean Charles de Menezes at Stockwell Tube station.

The commission examined Mr Hayman's conduct after the shooting and later accused the Metropolitan Police Assistant Commissioner of misleading colleagues and the public. Mr Hayman – who has spearheaded the fight against Islamic extremism since 2005 – has also been questioned over allegedly 'inflated' expenses claims and trips abroad with Sergeant Heidi Tubby, his staff officer.

His decision to step down is yet another blow for Sir Ian Blair who recruited Mr Hayman after taking over as Metropolitan Police Commissioner in February 2005. Last night Mr Hayman's former colleagues rallied to his support, claiming he had been the victim of a 'dirty tricks campaign' at Scotland Yard.

'For months Mr Hayman has been the subject of a witch-hunt designed to force him out of office,' said one. 'These matters could and should have been dealt with behind closed doors.'

Mr Hayman – a 48-year-old married father of two – has been caught up in two internal investigations this year.

The first was sparked after complaints that information about a series of anti-terror raids in Birmingham last February was leaked to the media in advance.

Mr Hayman's telephone records for the months before and after the raids were scrutinised and he was cleared of any blame. Investigators did, however, find details of the hundreds of 'unexplained' calls between Mr Hayman and the complaints commission official.

She has now left the police watchdog and works for the Association of Chief Police Officers.

In a separate inquiry, Yard auditors raised concerns over the £15,000 spent by Mr Hayman on drinks, restaurants, hotels and foreign travel.

He strenuously denied the expenses allegations and vowed to clear his name when details of the financial probe emerged last month.

But yesterday he decided to retire immediately as the £180,000-a-year head of the unit in charge of the fight against terror.

Channel 4 News claimed Mr Hayman was in very close contact with the complaints commission official, who worked for the watchdog's communications department.

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The pair's exchanges came when the commission was drafting its report into how the Met handled the aftermath of the shooting of Mr de Menezes in South London in July 2005. Channel 4 alleged the 'communications risked compromising the integrity and authority of the IPCC inquiry'.

Mr Hayman vigorously rejected the claims but, after a fiery meeting with Sir Ian on Monday night, decided to take early retirement.

He issued a statement saying the 'unfounded allegations' had taken their toll. The former Norfolk chief constable will spend the next four months on paid leave before officially retiring in April.

By then he will have served 30 years in the police and be entitled to a full pension.

In a statement, Mr Hayman said the time was right to leave the high-profile job after a string of hurtful accusations.

'This role requires total commitment in both time and effort and has a considerable impact on your personal life, your family and friends,' he added.

A spokesman for the complaints commission said the calls from Mr Hayman to its former member of staff appeared not to be workrelated.

Deputy Assistant Commissioner Peter Clarke, who had been due to step down next month, will postpone his retirement until Mr Hayman's successor is appointed.

Home Secretary Jacqui Smith said: 'Andy Hayman has been at the forefront of the police's work to protect our country from the terrorist threat.

'I am very grateful for his immense contribution to counterterrorism and to British policing.' Mr Hayman was awarded a CBE last year for his outstanding work after the London bombings of July 2005 and for his role in rounding up the failed July 21 gang. He is said to have impressed Tony Blair and leading Government figures with his calm demeanour and factual briefings to the Cobra emergency security committee that month.

In 2004, he received the Queen's Police Medal in recognition of his career achievements.

Last year he made a humiliating apology to two brothers arrested and later released after a high-profile anti-terror raid on their house in Forest Gate, East London.

One of the men was shot during the operation which involved a search for a 'chemical device'.

No such device was found.