An investigation has been launched into claims that Oxfordshire-based fans of Leeds United Football Club, are behind a hate-mail campaign.

Peter Ridsdale, chairman of Leeds United, has received letters threatening his wife and children over a controversial proposal to build a new stadium away from the club's Elland Road base.

Several of the letters and cards, which were sent to Mr Ridsdale's home and Elland Road ground, were signed 'Oxford Whites'.

West Yorkshire Police launched an investigation into the claims and yesterday an Oxfordshire man walked into Abingdon Police Station, offering to help with the inquiries.

A Leeds United official confirmed Oxford Whites banners had appeared at the club's games. Eric Carlisle, secretary of the Leeds Independent Supporters' Club, said the Oxford Whites were a rogue group not affiliated to the official supporters' club.

A spokesman for Thames Valley Police said: "A man has contacted Thames Valley Police at Abingdon Police Station and arrangements are being made for him to be interviewed by detectives from West Yorkshire later this week."

The mail sent to Mr Ridsdale was sent from around England and foreign cities where Leeds United were playing matches against European opposition last year.

Another group called the Lancaster Whites has also sent threatening correspondence to Mr Ridsdale.

Police used handwriting experts and DNA specialists to help their investigations.