A convicted killer, who was dubbed the Black Dog Strangler, has escaped from a secure hospital, Northumbria Police said.

Phillip Westwater, 44, fled St Nicholas Hospital in Gosforth at 10am this morning after asking to go to the toilet.

He left the clothes he was wearing in the toilet.

Westwater was detained indefinitely under the Mental Health Act following a pub fight in 1989, where he left a man paralysed for life after slashing him across the throat with a shard of glass.

The following year, he strangled fellow patient Derek Williams at Ashworth Hospital, Liverpool, with his dressing gown cord after he became convinced his victim had turned into a black dog.

Northumbria Police urged the public not to approach Westwater, who is described as white, 6ft and of slim build, with brown/grey hair.

Officers are making inquiries into this individual and any risks he may or may not pose. In the meantime people are asked to contact police on the 999 emergency number if they see him and not to approach him.

Northumbria Police's Superintendent Derek Scott told ITV Tyne Tees that the 'Black Dog Strangler' was "insulin dependent" and now went by the name Philip Whiteman and not his previous name Phillip Westwater.

The convicted killer was being escorted from his ward to a restaurant in a separate building - but still within the hospital grounds - when he went missing.

Police are understood to have contacted friends and family of the 'Black Dog Strangler' who live in the Tyneside area.

Westwater, who is from Newcastle, married a nurse while he was a patient at high-security Rampton Hospital in 2008.

Before being treated at Rampton, Westwater had also been a patient at Broadmoor.

St Nicholas Hospital in Newcastle is considered a medium-security unit.