MPS could have the final say on whether Wiltshire Constabulary survives as a stand-alone force.

The House of Commons will be given the final vote on how to re-organise south west police forces if the region's police chiefs block plans to create strategic forces.

It came as Home Secretary Charles Clarke announced mergers will press ahead in four areas of the country.

Mr Clarke said an assessment by HM Inspectorate of Constabulary concluded there was "only one acceptable option" for the North East, North West, West Midlands and Wales.

Home Office officials are still considering the future of five other regions including the south west.

Mr Clarke has written to Wiltshire's chief constable and police authority chairman to explain the "process and timescales for further discussions".

He added: "In the next few weeks I will meet with those chief constables and police authorities to agree a way forward."