Stagecoach is to freeze any further work on its proposals for a cross-Forth hovercraft from the end of this month.

The Perth-based transport group is putting all research and development on the project on hold until it receives clarification over the future public sector role and investment, both of which are key to taking the project forward.

Stagecoach unveiled a detailed business plan in autumn 2007 outlining how a link could be established between Fife and Edinburgh using a 150-passenger craft with a crossing time of just 20 minutes (Transit November 2).

Around £500,000 has already been invested by Stagecoach in the plans. The group has offered to invest a further £10m to make the project a reality, provided that there is public sector support of £3.3m to bridge the gap in the first three years to reach the point where it became commercially viable.

Despite support from across the political spectrum, an offer of public sector support has not yet been forthcoming. Meanwhile, a Stagecoach spokesman said the group had become "increasingly frustrated and angry at the cynical use of the hovercraft project as a political football".