Police investigating the attempted abduction of an RAF serviceman from an airbase have released e-fit images of the suspects.

It comes one week after the incident at RAF Marham in Norfolk, where two men, one armed with a knife, tried to bundle the man into a vehicle.

The suspects, both described as Middle Eastern in appearance, remain at large and their vehicle has not yet been located.

The first is described as aged between 20 and 30, about 6ft and of athletic but stocky build, with dark hair which was long on top, and a well-groomed beard. He had a dark skin tone and wore casual clothing.

The second is also described as aged between 20 and 30, but younger than the first suspect and of a slimmer build. He is about 5ft 10in and clean shaven with short dark hair, and was wearing a white T-shirt and dark shorts.

Police were carrying out further inquiries around the village on Wednesday.

Detective Superintendent Paul Durham, from the Norfolk and Suffolk Major Investigation Team, is leading the inquiry with support from officers from the Metropolitan Police Counter-Terrorism Command.

He said: "Today we have released e-fit images of the two suspects seen by the victim during the incident and I would urge anyone who recognises either man to come forward and call police immediately."

While the victim only witnessed two people during the incident, officers have said it is possible there was at least one other person in the vehicle.

Mr Durham added: "We know that our victim is a member of RAF personnel and we are still investigating how much relevance this was to his attempted abduction. It is probable that there would have been a degree of planning involved and, in order to achieve this, it is quite possible that there was at least one other person involved."

Officers are keen to speak to anybody who may have seen anything unusual and spotted the suspects or their vehicle.

"We've carried out extensive inquiries in the area but the purpose of these anniversary checks is to speak with people who regularly use roads in the area as part of a route to work or in their social life who we haven't necessarily captured as part of our house-to-house inquiries, said Mr Durham.

"We know from CCTV inquiries that this road, despite being rural, is well used, so it's possible someone may have seen the dark-coloured people carrier either being driven by the suspects or parked up in the area on that day."

The victim, a man in his late 20s, was out running between 2.45pm and 3.26pm last Wednesday when he was approached by the first suspect who grabbed him by the shoulder and wrist before pulling him towards the vehicle.

The victim managed to fight off his attacker, head-butting and punching him, which is likely to have caused visible facial injuries. The suspect was knocked to the ground and then the second suspect, who had a knife, appeared and went to the aid of his accomplice.

This allowed the victim to run away and get help.

Anyone who recognises either of the suspects or has information regarding their whereabouts should call police on 101 or the hotlines on 0800 056 0154 or 020 7158 0011. Officers have warned the men should not be approached but if sighted people should call 999 immediately.

Mr Durham said police continued to pursue several lines of inquiry as well as the incident being a potential terror attack.

"We're looking at the possibility of mistaken identity, a drugs debt or a domestic type thing," he added.

There was no firm evidence to establish the motive for the incident, he added.

He said the e-fits were based on information provided by the victim, and CCTV footage was still being reviewed.

"It's very challenging," he said. "It's patchy at best."

He said a large geographical area was involved, with multiple possible entrance and escape routes.

"We've not had that breakthrough that we need, hence the reason this appeal is so important," he said.

Asked if police had located any witness whose account corroborated the serviceman's account, Mr Durham said: "That's part of the trawl today. It's about getting all that information.

"There's a huge amount - not just living witnesses but CCTV and overlaying it.

"Given the very exposed and rural location this has taken place it's always going to be a challenge.

"We haven't identified that individual yet. They may be out there, they may not."

Asked whether he had any reason to doubt the account provided by the serviceman, he said: "Not at all."

He said the motivation for the attack was not known, and a line of inquiry that it was a drug debt was not a suggestion that the serviceman was involved in drugs but that it might be a case of mistaken identity.

Mr Durham said it would be "foolish" not to regard the two suspects as dangerous.

He said 20 anti-terrorism officers were assisting Norfolk Police with the investigation but there was "no credible evidence" that it was a terror attack.

The circulation of the e-fit images at other military bases in the UK was a "precautionary" measure, he added.

He confirmed there had been reported sightings of the vehicle within the parish but declined to go into specifics.

Police have contacted NHS England with regard to injuries one of the suspects may have suffered in the incident, Mr Durham said.

There were additional police patrols in the village.