The prime minister has convened a meeting of his Cabinet in a special political session to put the finishing touches to plans for Labour's party conference.

The meeting comes as the party faces the prospect of defeat in the Brent East by-election and a growing rebellion over plans to reform higher education funding.

Ministers are also braced for a wave of criticism over proposals to establish a wave of arms-length foundation hospitals. Following the meeting Tony Blair is set to send a defiant message to critics of his reform programme.

The prime minister will use a visit to open a new specialist school to repeat his warning that radical change is the only way the government can deliver on its goals.

"The bigger the challenge to achieve social justice, the bolder the reforms needed," he will say.

His comments will come at the opening of a £32 million business academy in Bexley, South London.

The prime minister will join with the education secretary Charles Clarke to outline plans for 25 further schools.

He will claim that the majority of secondary school children will be in either specialist schools or academies by the end of the year.

Ahead of the event, Number 10 revealed that Tony Blair was preparing to fight his critics who are planning to do battle with the government over the issue of public services at Labour's party conference.

"The prime minister will be making clear his message is not just for Bexley but public services as a whole," said the official spokesman.

"People can begin to see changes on their own streets and in their own hospitals."

On Wednesday Blair struck a defiant tone in the face of criticism of plans to charge university top-up fees.

During a meeting of the Parliamentary Labour Party Blair was repeatedly warned that the policy could be defeated in the Commons.

Peter Bradley, a PPS and member of the government's "payroll vote", said the prime minister should "return the favour" to MPs who supported him over the war.

Also on Wednesday, over 25 Labour MPs met at Westminster to plot their rebellion.

They believe that 130 MPs will oppose the move and insist they will be able to defeat the policy in the division lobbies.

Blair had moved to mollify his critics but failed to win them over.

Whilst he said he was open to "debate" on public service reform, he refused to cave in to demands for a U-turn on foundation hospitals and student top-up fees.

Speaking in the Commons the prime minister stood firm in the face of criticism from both Tory and Labour MPs.

"I'll explain the reason why graduates will pay more income tax, it's because they are earning a great deal more money, about 50 per cent more," Blair said.

"And the choice is very simple: we either get more funds to university and have a fair system where no-one pays money upfront, or we adopt the Conservative policy which will result, according to the Institute of Education, in a cut of 100,000 students every year."

After Blair's uncompromising performance, a senior Labour MP said he was correct to stick to his course.

"If you go on changing policy all the time, all you end up with is a hiatus," he said.