Four men being held in connection with the escape from custody of a convicted murderer have been released by police.

The arrests in the hunt for Shaun Walmsley, from Liverpool, were made in Poole on Friday afternoon.

Dorset police said armed officers stopped a silver Vauxhall Corsa at about 3.45pm on Friday in Canford Cliffs.

Officers fired tyre deflation rounds to stop the vehicle and detained the men on suspicion of aiding and abetting escape from lawful custody.

On Saturday, Merseyside police said the suspects – two men aged 24 from Toxteth, a 25-year-old from Maghull and a 25-year-old from Vauxhall – had been released pending further inquiries.

Walmsley, 28, went on the run on 21 February when two men armed with a knife and a gun confronted prison officers guarding him at Aintree University hospital during a visit from HMP Walton. The trio fled in a gold-coloured Volvo which was later found abandoned in the Fazakerley area of Liverpool.

Walmsley was serving life with a minimum term of 30 years for the murder of Anthony Duffy, 33, in May 2014. Duffy was lured to an address in Aintree and repeatedly stabbed and left for dead.

Merseyside police are said to be working with forces overseas in the search for the killer.

