Paul Boateng: angry

The union, which is not allowed by law to take industrial action, fears the government's proposals will almost certainly lead to the prison being privatised, which they say will result in wage and staff cuts and increase the risk of assault.

As part of its 'work to rule' campaign launched on Wednesday, prison officers were urged to withdraw goodwill.

Pay statement delayed

But Prisons Minister Paul Boateng who is angered by the move, held back from making an expected statement on pay and industrial relations in the service.

The POA had expected the Minister to announce moves to review Section 127 of the Criminal Justice Act which outlaws industrial action in prisons.

Duncan Keys, POA assistant secretary, said: "The Home Office is surely not surprised that we are against market testing at Brixton because we believe it will only guarantee lower pay, lower staff numbers, worse conditions and increased risk of assault. I am surprised if they did not think we would react."

The POA must understand it is this Government's firm intention and resolve to modernise the prison service.

Paul Boateng Prisons minister

Prison officers were also urged to contact their local media and MP.

Mr Boateng said: "The POA must understand it is this Government's firm intention and resolve to modernise the prison service.

"Brixton will be market tested, no-one should be under any illusion about that, nothing is going to stop that," he said.

"This campaign is, in that respect, utterly misguided."

Last November, Mr Boateng warned Brixton's governor Bob Chapman that if the situation at the prison was not significantly improved over the next year, private companies would be invited to take it over.

But Mr Boateng, together with Prison Service director general Martin Narey, decided to take the step early.

They were apparently shocked by the failure of the 788-inmate south London prison to address acute problems of cleanliness, poor health care and racism.

The go-ahead for market-testing, which will see private firms competing with the Prison Service for the contract to run Brixton, is expected next week.