A health minister is facing the humiliation of being ousted from a prestigious role within the Royal College of Physicians over claims that he falsely reassured doctors who feared the coalition would privatise of the NHS.

Earl Howe's position on an advisory committee is being reviewed following a complaint. Six influential members of the professional body that represents doctors wrote to its president, Sir Richard Thompson, claiming that the minister was "not a fit person to fulfil this important role". Thompson has launched an investigation by the College's trustees into Howe's probity.

The senior doctors claim that Howe, a former banker, falsely advised them that reforms under the health and social care bill would not force doctors to use market mechanisms to choose where patients will be treated.

According to the doctors, the regulations will mean that clinical commissioning groups – the bodies to be set up by GPs to organise patients' care – will have to put services out to tender if there is more than one provider capable of offering particular treatments. This means NHS hospitals and services will have to compete with private health firms for business.

Andy Burnham, the shadow health secretary, said there had been a breakdown in trust between health professionals and government, adding: "This whole issue has become a crisis of trust for the department of health. There would be a straight forward breach of trust given that statements ministers have given have not been honoured.

"The medical profession feels the government has mis-sold its NHS reforms. It was sold on the principle that doctors would be in control but in fact it will be the market that will decide."

A spokeswoman confirmed that Thompson, and "in the interest of probity", had "referred the issue to the board of trustees and would report back in June".

She said the Friends of the RCP, the committee on which Howe serves, is an informal advisory group, including past presidents and officers, and figures from finance, industry, and other charities, that plays no role in the governance or management of the RCP but offers advice in areas such as effective fundraising.

The coalition denies the regulations will force doctors to put services out to tender, believing it will give GPs the ability to select a variety of providers and will improve standards.