It is alleged that Martin Winter should have included in his election returns a meeting at Doncaster Rovers ground.

In his speech at the meeting, during the election period last May, the club's chairman, John Ryan, told fans to vote for guest speaker Mr Winter.

Police are looking at a whether the meeting, paid for by the club, was an undeclared election expense.

Council silence

In a statement, a spokesman for South Yorkshire Police said: "Following information received, South Yorkshire Police are investigating under the Representation of the People Act.

"The investigation is on-going and we are unable to provide more information at this stage."

Doncaster Metropolitan Borough Council refused to comment.

Dave Morris, chief executive of Doncaster Rovers dismissed the allegations and told BBC News that Mr Winter "does a great job for Doncaster".

"It was purely a rally to get fans going for the 2005/06 season and generate interest in the club and we asked Mr Winter along to answer a few questions about plans for a new stadium," said Mr Morris.

"Martin Winter does a great job for Doncaster and it is about time people got off his back."

In a separate inquiry, police are already investigating the way a community project, once run by Mr Winter, was set up after being criticised by a government watchdog.

The Audit Commission criticised the high administration costs of the project, but no individuals have been singled out.