Conservative MP David Ruffley’s constituency association received a £10,000 donation from the wife of a former care home company boss.

A group of opposition councillors are now asking how the business, Care UK, was chosen to take control of Suffolk’s 16 council-owned care homes.

The £10,000 donation made to Mr Ruffley’s Bury St Edmunds constituency association in November 2009 by Caroline Nash – wife of John Nash who was chairman of Care UK at the time – is listed on the House of Commons Register of Members’ Financial Interests.

The county council’s Conservative Group says it knew nothing of the donation, and both the Conservative party and the county council have stressed they have not breached any rules.

Last night, Mr Ruffley said he had absolutely no knowledge of how, or when, Care UK was granted contracts in Suffolk, which was “entirely a matter for Suffolk County Council to answer”.

A county council spokesman said the transfer of care homes to Care UK was a “thorough, rigorous and transparent process” administered by professional officers of the county council and supported by independent consultants KPMG.

But the county’s Green & Independent Group has called for the Tories to publicly declare the total amount of money they have received from Care UK and its associates.

The group’s leader, Mark Ereira-Guyer, pictured, also wants the council to explain the process it used in selecting the care home provider.

He said: “Care UK’s private equity owners stand to make a considerable amount of money by selling care home sites it has bought, such as Angel Court in the middle of Hadleigh, and from its three-and-a-half year contract to provide beds for Suffolk’s vulnerable older people. The questions we would like answered are how many other donations have there been and why did the Conservative council choose Care UK?”

The county council spokesman said councillors had been given an opportunity to scrutinise the care-home provider decision-making process.

He said: “A comprehensive public consultation was carried out with customers and their families. Final decisions were taken by cabinet members, in public, based on professional advice to the council. It had nothing whatsoever to do with donations to any political parties.”

A spokesman for the council’s Conservative Group said donations made to Conservative constituency associations were “fully transparent” and there for all to see.

He added: “At no point would such a donation have had the slightest connection with the work of county councillors or decisions being made at the county council. The decision to appoint Care UK was conducted extremely transparently and, as befitting such an important issue, done with the utmost care and consideration.”