The UK government announced plans on Wednesday to build four new prisons by 2031 to ease an overcrowding crisis, which triggered the early releases of hundreds of inmates this year.

Justice Secretary Shabana Mahmood set out the 10-year plan to ensure there is "always a place in our prisons for dangerous offenders", with the prison population in England and Wales ballooning in recent years.

The measures involve finding 14,000 additional prison spaces in the next seven years, including 6,500 places through the four new prisons.

It is part of a programme launched by the previous Conservative government to create 20,000 new prison spaces - a scheme which it is now estimated could cost up to £10.1 billion ($12.8 billion), double the original budget.

Mahmood said prisons will be classified as sites of "national importance" to fast-track the building process but she warned the measures will not be "enough".

"We will build but the sad situation here is we cannot build enough to keep up with the pace of demand which is rising very, very quickly," Mahmood told Times Radio.

She blamed the precarious situation on the previous Conservative administration, accusing them of completing less than a third of 20,000 prison spaces they had set out to build.

"The last government pretended they could send people away for longer and longer without building the prisons they promised," said Mahmood.

"They left our prisons in crisis, on the edge of collapse," she added.

As of Monday, there were 86,089 prisoners across England and Wales held in jails which had space for 88,822 inmates, according to official data.

Only days after taking up her post in July, Mahmood announced emergency measures releasing inmates early to prevent a "collapse" of the prison system when it was discovered there were only 700 places left in men's jails.

However, she said the government would try to avoid any similar moves in the future.

"I don't want to be in a position where we ever do emergency release of the kind that we've had to do," Mahmood told Sky News.

"There are other operational measures that we might have to take to try and stabilise the prison system", like expanding house arrest provisions, Mahmood added.

AFP