An emergency plan to avoid prison overcrowding could be triggered as early as “next week” as more rioters are sentenced, the Prison Officer’s Association has said.

Operation Early Dawn, a contingency that allows defendants to be held in police cells until prison spaces become available, could be used.

The government announced quick sentencing for those involved in the riots that followed the fatal stabbing of three girls in Southport, leading to hundreds appearing in courts across the UK.

But the POA’s national chairman told BBC Radio 4’s Broadcasting House on Sunday prgramme, this risks “clogging up prison cells”.

Mark Fairhurst said he wouldn’t be “surprised” if the Ministry of Justice at some point tomorrow morning announces that “Operation Early Dawn kicks into play at some point next week.”

A Ministry of Justice spokesperson told the BBC they will “update on operational decisions in the normal way”, adding that the government “will always make sure we have the prison places we need”.

During Operation Early Dawn, defendants would not be allowed to leave the police cells for sentencing unless it was confirmed there was a prison bed available for them.

Mr Fairhurst warned that this “has a massive knock-on effect on the entire justice system” as police cells get clogged up, meaning officers “haven’t got the power to arrest people and put them away”, he explained.

He said last week saw 397 new receptions, the “biggest influx” he had seen for some time, and that on Friday, the adult male closed estate only had 340 spaces left.

Pressure on the prison system is “really, really tight”, he warned, adding offenders could be sent hundreds of miles from home to serve a sentence in a prison with spaces.

Justice Secretary Shabana Mahmood announced plans to cut the proportion of the sentence inmates must serve behind bars from 50% to 40%.

The temporary move – which does not apply to those convicted of sex offences, terrorism, domestic abuse or some violent offences – is expected to result in 5,500 offenders being released in September and October.

Last Monday, the government confirmed those involved in recent unrest will not be excluded from its plans to release some inmates from jail early.

MPs have already approved the laws allowing the plan to be put into action and any changes could require updating the legislation in a short space of time if additional exemptions were to be included.

Operation Early Dawn was previously triggered by the Conservative government in May in a bid to tackle overcrowding in jails.