Tony Blair yesterday prepared for battle with unions opposed to his plans to give private firms a bigger role in delivering public services.

In a keynote speech to Labour's local government and women's conference, in Cardiff, he insisted that reform was crucial to delivering world-class schools, hospitals and transport links.

He warned that this parliament would be dominated by a battle of "reformers versus wreckers".

Labour officials stressed that Mr Blair used the phrase in the context of an attack on the Tories' approach to the public services.

However, Transport Secretary Stephen Byers used the same words in a speech on Saturday in what was clearly a reference not only to the Tories, but also union leaders who are campaigning against private sector involvement.

Mr Blair acknowledged that the Government faced an alliance of the right and far left, each opposed to the reform agenda for different reasons.

TGWU general secretary Bill Morris said that he and fellow union leaders were locked in a determined battle with the Government over the issue.

Mr Morris, speaking at a Cardiff rally in support of workers sacked at Caernarfon automotive products company Friction Dynamex, said: "We are not the wreckers.

"The wreckers are the Railtracks, the Enrons, the Craig Smiths (Friction Dynamex boss), and those who believe that September 11 was a good day to bury bad news.

"They are the wreckers and they will wreck our party and our country."

The public sector unions are also set to intensify their campaign to highlight examples of where they believe services and working conditions have deteriorated after private companies have moved in, particularly in hospitals.

GMB general secretary John Edmonds, who on Saturday warned that the promotion of the private sector would be Labour's version of the poll tax, said: "How can the Prime Minister expect us to forget about privatising public services when every other day another Government minister is handing over more of our public services to the private sector?"

In Mr Blair's speech, which earned him a standing ovation from activists in the auditorium at Cardiff's International Arena, he laid out a series of principles which would shape reform of schools, hospitals and transport during Labour's second term.

One was increasing diversity of provision to give service users more choice. He said that would include - where it was sensible and provided value for money, and with guarantees that staff were properly treated - using the voluntary and private sectors.

He told delegates: "Forget the nonsense about privatising public services under this Government."

However, he insisted: "If we are to win the argument for collective provision, defeat the wreckers and secure the future of our public services, then we must be prepared to use all available means to make the improvements that patients and pupils and passengers demand. And we will."

Mr Blair said the battle lines between the Government and the Tories were clear.

"Our strategy is to build up the public services. Theirs is to knock them down. Reformers versus wreckers."

Conservative Party chairman David Davis dismissed Mr Blair's speech as ''the usual mix of meaningless words and aspirations".

He said: ''Blair's effort in his speech to portray himself as a reformer of the public services is unbelievable. The public know that Labour have failed to deliver and its patience is running out.