On the run: Britain’s most wanted murderer 'spotted in Marbella, Thailand and Dubai'

A suspected killer who has been on the run for more than two years is being hunted in a number of countries by detectives after nearly a dozen sightings were reported.

Shane O’Brien, 30, is alleged to have killed 21-year-old Josh Hanson in an unprovoked knife attack in a bar in Hillingdon, west London, in 2015.

O’Brien, originally from Ladbroke Grove, fled on a private plane from Biggin Hill Airport immediately after Mr Hanson’s death and is on Interpol and Europol’s most wanted lists.

Since O’Brien was added to Interpol’s list, which has worldwide coverage, there have been 15 potential sightings reported to police or the National Crime Agency, who are working abroad to track him down and bring him in.

Four of these have been investigated and eliminated from enquiries but work continues on the rest, Scotland Yard said.

The Met said efforts are focused on Marbella in Spain, Bangkok in Thailand and Dubai.

A £50,000 reward remains on offer for information leading to O’Brien’s arrest and prosecution.

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O’Brien was arrested in Prague for criminal damage and assault in February last year under the Italian alias Enzo Mellonceli and released on bail.

Police now believe he was in the city for at least seven months, and extensive appeals have been carried out in Prague to try to build up a picture of his lifestyle.

Another person came forward to say O’Brien may have been in Gibraltar around the same time.

Information was also received that O’Brien may have been in Nice in early November, and officers are also investigating reports of sightings in Bari, Italy.

Detective Chief Inspector Noel McHugh, from the Homicide and Major Crime Command, said: ‘We are really pleased with the response to our appeals since O’Brien was placed on Interpol’s list and would urge people to keep their eyes open wherever they are in the world.

‘Please don’t be discouraged by the fact some potential sightings have been investigated and discounted – we want to hear from anyone and everyone who thinks they see O’Brien or has any information no matter how small.

‘We would encourage everyone to save the ‘wanted’ poster to their phones so they have all the information they need, and importantly if you are abroad and think you see O’Brien tell local police or call the National Crime Agency’s public line on 0370 496 7622, which is staffed 24 hours a day, immediately – it is really important we are able to act quickly.’

DCI McHugh said detectives are looking to people in nightclubs and boxing gyms as well as ex-pats and any women he may have become involved with to come forward.

He added: ‘Those who have been in close proximity to him may well have seen his distinctive and rather poor quality cover-up tattoo of an owl holding a skull.

‘As always, any calls we receive with information will be dealt with in the upmost confidence.’

Tracey and Brooke Hanson, Mr Hanson’s mother and sister, said: ‘Josh has not been a part of our lives now for two years and eight months and every day it is getting harder to cope without justice for him.’

O’Brien is described as white and 6ft with grey eyes and dark brown hair.

Mr Hanson, from Kingsbury, north-west London, was stabbed in the neck at the RE Bar in the early hours of October 11 2015 and died from his injuries at the scene.

A post-mortem examination gave cause of death as haemorrhage, inhalation of blood and an incised wound to the neck.

O’Brien featured on the Crimewatch Roadshow on BBC1 on Monday June 18 on its wanted section.