Clemenger Communications, Photon Group and Mitchell & Partners have ruled out merging or setting up a joint venture with John Singleton's sprawling marketing services firm, STW Communications Group.

The recent speculation about the fate of STW has been fuelled by executive chairman Russell Tate's comment to The Australian Financial Review last month that it was thinking about privatising, and Mr Singleton's comments that it might look at alliances with Clemenger, Photon and Mitchell.