Tony Blair's public sector reforms are based on a "twisted ideology" which promotes the private sector but demoralises staff morale, a leading trade unionist has said.
Unions are raising concerns about foundation hospitals plans
Unison boss Dave Prentis - who represents many public sector workers - also suggested that the government's foundation hospitals should be renamed "private hospitals".
The role of the private sector in the delivery of public services and plans for foundation hospitals are expected to come under repeated fire during debates on the third day of the TUC congress in Brighton.
In his speech, Mr Prentis said: "The government talks of modernisation, reform, markets - what they really mean is more competition, more fragmentation, more privatisation."
He added: "I'm incredulous at the efforts of some in government to focus not on what is being achieved, not on what is being delivered, but on a twisted ideology that promotes private sector delivery, that denigrates and demoralises staff."
Later in the day the war and ongoing occupation of Iraq will be debated by congress.
On Tuesday Chancellor Gordon Brown insisted in a speech to delegates that the government would press on with its public sector reforms.
But Mr Prentis warned delegates about creeping privatisation and said that plans for foundation hospitals will not improve the health service but create a two-tier system.
"Creating choice for the few but mediocrity for the rest," he said.
T&G boss Sir Bill Morris told delegates that the NHS was the "line in the sand, our last line of defence for public services".
"Foundation hospitals are not just a step to privatisation, they will be a dagger in the heart of the NHS - that's why we oppose them," said Sir Bill.
FBU leader Andy Gilchrist warned of "dangerous times ahead" if the government went forward with its plans to reform the fire service.
He said that modernisation under New Labour meant "fewer firefighters and greater danger".
On Tuesday, union leaders were left confused after Tony Blair apparently pulled back from strong words he had been due to use in a speech to them at a private dinner of the TUC governing council.
In a copy of his speech, released in advance to the media, he was due to tell the unions not to delude themselves about having a more left-wing government.
"The idea of a left-wing Labour government as the alternative to a moderate and progressive one is the abiding delusion of 100 years
of our party. We are not going to fall for it again," he was expected to say.
"Sensible trade unions - and most Labour Party members - know this government is doing its best for working people."
However, several people at the dinner said he did not make the comments and that Mr Blair's tone had been far
less confrontational than the pre-released extracts had suggested.
Billy Hayes, general secretary of the Communication Workers Union, described
the prime minister's speech as "warm" and was one of many officials surprised
when shown details of the comments released to the media.
Mark Serwotka, general secretary of the Public and Commercial Services Union,
said it had been "extraordinary" that Mr Blair did not deliver the original speech and suggested the discrepancy had been made deliberately.
"It is quite clear they are spinning certain messages. Those who thought the
end of spin was nigh have been given a nasty shock. None of the language was
Downing Street confirmed that Mr Blair had not used the exact words in the text released to journalists but insisted that the underlying message had
remained the same.
"It may not have been exactly the words on the sheet but the central message
was the same. There was no question of it backing down," a spokeswoman said.