Jack Straw has abandoned plans to build three giant “Titan” prisons, each holding 2,500 inmates, after criticism from prison governors and penal reform groups.

The £1.2 billion programme for the biggest jails in Britain was the centrepiece of a huge expansion of prison places to 96,000 by 2014. Mr Straw, the Justice Secretary, will tell MPs next week that instead of the three Titans, the Government plans to build “mini-Titans”, each holding 1,500 inmates.

He will announce the sites for two of the new jails next week, providing a future justice secretary with the option of scrapping the remaining three if the prison population stabilises. The mini-Titans are planned for the South East, North West and West Midlands and will be built and run by the private sector.

They form part of the biggest prison-building programme in Western Europe. In addition to the five 1,500-place jails, the Government is planning to build eight smaller prisons to house 5,400 inmates.

The Ministry of Justice said that total prison capacity would still increase as planned. “We have consulted on plans for new prisons and have listened carefully to all views,” a spokesman said.

A Whitehall source said that Mr Straw had never been ideologically wedded toTitans. He had listened to people such as Dame Anne Owers, the Chief Inspector of Prisons, and decided on the grounds of efficiency, effectiveness and security that it was better to build jails with 1,500 places, the source said.

A consultation paper on Titans last June said that each jail would be built on a 50-acre site. The jails would have been up to five storeys but divided into five separate units each holding about 500 inmates. Ministers argued that a Titan site could have held self-contained remand jails, youth jails and prisons for adults, allowing for savings to be made on shared services such as catering, education and administrative functions.

Whitehall sources said that the five new prisons were expected to cost “roughly the same” as the Titans. It was unclear how the economies of scale provided by three Titans could be achieved by building five 1,500 superjails. The Titans, a name Mr Straw disliked, were part of a programme intended to fill a predicted 13,600 shortfall in prison places by 2014. Twenty of the 135 jails in England and Wales hold more than 1,000, including the biggest, Wandsworth, with 1,643 inmates, followed by Birmingham with 1,400 and Wormwood Scrubs with 1,225.

The prison population yesterday was 82,773, a rise of 21 on the previous week. Of the prison estate, 88 out of 135 prisons are overcrowded and more than a quarter of inmates are in cells holding one more than they were designed for.

Penal reformers welcomed the abandonment of the Titans but said that building mini-Titans was not an answer to overcrowding. Frances Crook, director of the Howard League for Penal Reform, said that Titan jails were a disastrous idea and were now a “titanic policy failure”.

Ms Crook added: “Building five 1,500-place prisons, bigger than any other jail in the country, is not the answer to the chronic problems of overcrowding and violence in our jails.”

Dominic Grieve, the Shadow Justice Secretary, said: “Warehousing offenders in hulks twice the size of Wembley Stadium was never going to address increased levels of reoffending and so we welcome plans to scrap Titan prisons.

“However, Jack Straw needs to urgently explain how he will address the crisis in the prison population that has resulted in thousands of prisoners being released early. Only by increasing capacity, reducing overcrowding and replacing our old, expensive and ineffective prisons can we reform offenders and cut crime.”

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