Soccer:Garry Cook has resigned as chief executive of Manchester City, the club have announced. He had been the subject of internal investigation after sending an offensive e-mail to the mother of defender Nedum Onuoha.

The club have issued a statement confirming the board had accepted Cook’s resignation. It was reported that Cook initially claimed his e-mail had been hacked into but has now admitted to an “error of judgement.”

Cook has also been criticised in the past for a number of public relations gaffes. He admitted: “I am privileged to have held my position at Manchester City Football Club and to have experienced the opportunities that it has presented. The privilege is in part offset however by the significant personal focus which has at times, detracted from the magnificent achievements of those working at the football club.

“It is that factor, together with my error of judgement in this matter that has prompted me to reach this decision, which I believe is in the best interests of the football club.”

Cook was appointed by previous owner Thaksin Shinawatra in 2008 and remained in position after overseeing the takeover by the Abu Dhabi United Group later that year.

He continued to impress the new owners, steadily guiding the club towards their present position at the top end of the Barclays Premier League, but has occasionally made headlines for negative reasons.

These included referring to Thaksin, later found guilty of corruption in a Thai court, as a “nice guy”, criticising former player of the year Richard Dunne and accusing AC Milan of “bottling it” over the possible sale of Brazil playmaker Kaka to City.

Chairman Khaldoon Al Mubarak said: “Garry has made a remarkable contribution to Manchester City Football Club over the past three years. His judgement in this matter should in no way lead to his accomplishments being overlooked.

“On every level, the club is unrecognisable from the organisation which he inherited and our staff and supporter services, community outreach and commercial activity have seen unparalleled growth under his direction with yet more projects to be realised on the horizon.

“On behalf of Sheikh Mansour (owner) board, I would like to thank him for his energy and tireless commitment to serving all those connected with the football club. He will always be welcome at Manchester City.”

City director John MacBeath will fill the role of temporary chief executive officer while a replacement is sought.