Charlie Casey ran from HMP Sudbury last month and may have stabbed a woman since, while Paul Oddysses absconded from Hollesley Bay prison on Saturday

Police admitted on Saturday that two dangerous criminals have escaped prison, including one who may have since stabbed a woman. The two cases, which are unrelated, are the latest in a recent spate of prisoners absconding that has embarrassed the government.

Charlie Casey, 22, escaped from HMP Sudbury open prison in Derbyshire last month, where he was serving a four-year sentence for robbery and false representation. Police have now revealed they believe he went on to attack a 24-year-old woman in St Leonards, Dorset, on Wednesday evening. The victim, from Wales, suffered a non-life-threatening injury to her body and was taken to Poole hospital.

Dorset police said they believed Casey was in the Binfield and Slough areas, to the west of London. But officers said they thought he had now moved on to Gwent, in Wales, and urged the public not to approach him. He was described as white, 6ft 1in and of average build, with short, dark brown hair, blue eyes, and an Irish accent.

Detective Sergeant Andy Bell said: "Officers are searching for Charlie Casey and we are following positive lines of inquiry. If members of the public see anyone matching the description, or anyone hiding or acting in a suspicious or unusual way, then I would urge them to call their local police straight away. I would like to appeal directly to Charlie to make contact with the authorities as soon as possible."

In a separate case, Paul Oddysses absconded from Hollesley Bay prison on Saturday morning, where he was serving a life sentence for attempted robbery and robbery with a firearm. Police described him as white, of thin build, with brown hair, brown eyes and clean shaven. He also bore a scar on the back of his head and tattoos on both arms. Suffolk police said he had connections in the Hertfordshire and Essex areas.

The two are the latest in a series of cases of prisoners absconding. Michael Wheatley, known as the Skullcracker, absconded from HMP Standford Hill on the Isle of Sheppey earlier this month. He escaped while serving 13 life sentences for bank raids, but was recaptured and charged with carrying out another attempted armed robbery.

Two other prisoners, Damien Burns and Dean Jackson, absconded on Tuesday. Burns was serving an indeterminate sentence for a knife-point robbery, while Jackson was on remand awaiting a sentence for a theft-related offence.

Conservative MP David Mowat said the spate of prison escapes reflected badly on the government. "In their own words, the government have said it's not adequate and it's not acceptable," he said. "What I think is it should be done quickly."

"Accountability seems to be missing. A mistake has been made, but are we learning from it?"

Conservative backbencher Philip Davies has criticised the decision to relax security over Burns as "disgraceful". He said: "It is completely ludicrous that a serving life sentence prisoner is even in an open prison where they can simply walk out.

"As far as I am concerned whoever allowed him to be in an open prison should be sacked, it is a complete disgrace.

"The top priority for the prison service should be the protection of the public. [Justice secretary] Chris Grayling needs to put in charge of the prison service someone who will see protection of the public as a top priority."

Shadow justice secretary Sadiq Khan demanded an immediate independent inquiry into the recent spate of prison escapes, which he said were "now beyond a joke".

"This is now beyond a joke and a full, independent and immediate inquiry into these escapes is the only way the public's confidence can hope to be restored," he said.

"It's crucial they're recaptured as quickly as possible but the public have lost confidence in this government being able to do even the most basic things right."

Figures released by the Ministry of Justice in 2013 showed that 679 prisoners escaped from open prisons, or disappeared while on day release, over the previous three years. More than 1,000 criminals in open prisons have a history of violent offending.

A Ministry of Justice spokeswoman said: "The justice secretary has been clear that keeping the public safe is our priority and has ordered immediate and major changes to tighten up temporary release processes and open prison eligibility.

"Absconds have reached record lows under this government - down 80% over the last 10 years - but each and every incident is taken seriously, with the police contacted as a matter of urgency."

"Open prisons and temporary licence are an important tool in rehabilitating long term offenders but not at the expense of public safety."