The federation claims just 1 in 20 consultants backs the policy

The letter, published in The Times, says the introduction of foundation trusts will be "a damaging step".

The NHS Support Federation, a lobby group which gathered the signatures, urged ministers to "rethink these damaging reforms".

The letter comes just hours before a crucial Commons vote on the issue.

Increase inequalities

The letter says foundation trusts will damage patient care and increase inequalities.

"We fear that for many patients it will reduce the quality of care and undermine the provision of a comprehensive health service that is available to all," it says.

We fear that for many patients it will reduce the quality of care NHS Support Federation letter

"Some hospitals may thrive, but at the expense of others," it continues.

"The threat to effective strategic planning may force patients to travel outside of their local area for treatment."

It adds: "A well resourced NHS has already shown its ability to be innovative and flexible in providing for the health needs of individual communities. We should seek to build on this potential."

In his letter to The Times, Professor Harry Keen, president of the federation, suggested few doctors support the government's plans.

"The letter backs research by the NHS Support Federation, which found that only 1 in 20 consultants supported the government�s plans as they stand.

"The survey also showed that 76% said it would lead to a two tier service," he said.

"We urge the government to rethink these damaging reforms and listen to the consensus which warns of an NHS under this plan, that in many instances will be less able to meet the health needs of local people."

MPs will vote on foundation trusts later on Wednesday.

There is growing speculation the government's plans could be defeated.

A substantial number of backbench Labour MPs could vote against the government because they fear the proposals will lead to a two-tier NHS.

Under the plans, foundation trusts would be allowed to opt out of government control and becoming independent not-for-profit organisations.

They would be able to borrow money on the private markets and set their own financial and clinical priorities.

They would remain part of the NHS and be monitored by stakeholder councils, whose members would be drawn from local communities.

Many Labour backbenchers and trade unions are vehemently opposed to the plans.