Sir Keir Starmer has refused to rule out high-risk criminals being released early from prison amid the overcrowding crisis in jails.

The Labour leader, widely expected to become Britain's next PM tomorrow, also left the door open to prisoners being released less than halfway through their sentence.

His failure to rule out high-risk criminals being released early came despite him having urged Rishi Sunak to commit to the same pledge earlier this year.

During PMQs on 15 May, Sir Keir demanded Mr Sunak offer a 'guarantee' that 'none of the criminals who he is instructing prisons to release early is considered high-risk'.

The Government has acted in recent months to release prisoners early due to the ballooning jail population as a result of tougher sentences and court backlogs.

Many of the UK's jails are near full capacity, with reports this week a 'one-in, one out' system - known as Operation Brinker - could be introduced for the first time ever.

On the final day of general election campaigning yesterday, Sir Keir was asked by The Times whether he would give the same guarantee on high-risk criminals as he had previously demanded of Mr Sunak.

The Labour leader said, if he wins power, he would 'instinctively' want to ensure high-risk prisoners were excluded from the early release policy, which allows some inmates to be let out up to 70 days early.

Sir Keir pointed to the case of a domestic abuser who was released from Lewes prison this year despite being deemed a risk to children.

But he also added: 'I'm not going to sort of announce and get ahead of myself on what we'll need to do but it's a very serious problem when the Government has allowed the prison system to get so full, a lack of preparation, that we are having to release people who should be in prison.'

On the campaign visit to Carmarthen, South Wales, Sir Keir was also quizzed about whether he would consider lowering the automatic release point for most offenders from 50 per cent of their sentence to between 40 and 45 per cent.

Such a move was recently recommended by the Institute for Government think tank among a series of proposed measures for freeing up thousands of prisons places.

Sir Keir said: 'I'm very concerned about the situation, because it is appalling that we are in the place we are where the Government has allowed a situation where we don't have enough prison places for the people who need to be in prison.

'That is a shocking indictment of this government, criminal justice should never be in that place.

'In addition to that, they are saying to the police 'Don't arrest people', because they can't put more people into prison places.

'To actually say those things in 2024 - and I worked in criminal justice for five years -  releasing prisoners early and telling police not to arrest people, is a terrible state of affairs.

'We are going to, if we get into power… inherit that. In terms of the specific things that we will do, we will have to wait and see what that is, but I can't stand here and pretend to you or everybody else that we can build a prison in 24 hours after the election result is called.

'We have to get on with the hard yards of sorting this mess out, but it is one massive mess.'