The state government has slashed the number of beds to be built at the new Cherry Creek youth justice centre.

The Cherry Creek facility, which is being built about 1.5 kilometres north east of Little River Road where it joins the Princes Freeway, is due to be completed in 2021.

The state government last week announced the justice centre would have just 140 beds when it first opens.

Previous state government plans said it would have up to 300 beds for remanded and sentenced children and young people, a 12-bed mental health unit and an intensive supervision unit of at least eight beds.

Western metropolitan region MP Bernie Finn said the state government “is all over the shop on youth justice”.

He said the government’s “backflip” on a previous commitment to close the Parkville Youth Justice Centre showed they were “flip-flopping all over the place”.

“This is a dog’s breakfast,” he said.

“If you want to know what is going to happen with youth justice in this state, stay tuned because it could change tomorrow.”

Last week’s state government announcement also revealed the Cherry Creek facility would house males aged 15 to 18 years old and would be an “interim youth justice system configuration”.

“The design of the Cherry Creek facility has been revised to deliver a more specialised facility that focuses on staff safety and reducing re-offending among Victoria’s most complex and challenging young males aged 15-18 years,” the government said.

“The facility will also include an intensive intervention unit, a specialised health care unit, intensive alcohol and drug treatment and dedicated mental health beds.

“Security and safety for staff and rehabilitation of young people is at the forefront of the revised design. There will be more secure accommodation units, advanced technology to monitor movement, additional CCTV, improved security counter designs at reception, gatehouse and admissions areas and new staff exit points.”

The centre will also be “master planned” to have up to 244 beds in the future.

The Minister for Corrections and Youth Justice Ben Carroll said: “This facility will manage the most complex and challenging young people in custody to prevent reoffending and keep the community safe.”