Mr Straw told BBC Radio 4's Today programme this morning (30 January) that: "We haven't got planning permission for these places. We are not definitely going ahead with them."
He added that: “The risk is that we will move towards large-scale penal containment, spending more to accomplish less, losing hard-won gains and stifling innovation."
He said: "We're not going to have large warehouses as they have in the United States and indeed France."
The titan prisons were proposed as part of measures to reduce strain on the penal system, which is operating at close to capacity.