A gay activist's undercover video is drawing unwanted attention to a counselling clinic co-owned by Republican presidential candidate Michele Bachmann.

The activist visited a Minnesota clinic run by Mrs Bachmann's husband Marcus and filmed therapy sessions apparently geared toward helping the activist overcome homosexual urges.

The activist was working on behalf of a gay advocacy group, Truth Wins Out, which has tried to discredit therapy that seeks to "cure" gay people.

Neither Bachmann would do interviews about the video.

In the past, Marcus Bachmann has denied his clinic conducts so-called "reparative therapy".

The American Psychological Association says no solid evidence exists that individuals can change their sexual orientation.

Mrs Bachmann, seen as a standard bearer of the radical 'tea party' movement, has announced she is running for president.