Suspect One: Aged between 20 and 30, around 6ft tall, athletic but stock build, with dark hair which was long on top. He had a well-groomed beard, dark skin tone and wore casual clothing. Suspect Two: Aged between 20 and 30, younger than his accomplice, and a slimmer build. About 5ft 10ins tall, clean shaven with short dark hair. He wore a white T-shirt and dark shorts.

Renewed appeals have resulted in more than 100 calls to special lines set-up in the wake of the attempted abduction of a serviceman outside RAF Marham.

The response followed the release of e-fit images of two suspects on Wednesday.

The images were published on the one-week anniversary of the attack, on July 20 between 2.55pm and 3.26pm in Squires Hill.

Detective Superintendent Paul Durham, of Norfolk and Suffolk Major Investigation Team, said he was pleased with the response.

He said Wednesday afternoon’s work had resulted in 150 calls and information was being followed up.

Officers handed out leaflets with the images, conducted roadside checks  on Wednesday and were examining dash cam footage.

“We continue to make progress but this will be a lengthy investigation as it requires painstaking detailed enquiries,” said the police chief.

Two suspects have both been described as of Middle Eastern origin in appearance and aged 20 to 30. The vehicle they used has not been traced and police have appealed for people to come forward if they saw a dark-coloured people carrier in the area on the day of the attack.

The victim, in his 20s, was running on a outside the base when he was grabbed by the bearded suspect (pictured) who pulled him towards the vehicle.

The victim managed to fight-off the attacker by head-butting and punching him.

The attacker was knocked to the floor. The clean-shaven suspect (also pictured), armed with a three-inch bladed knife, went to help his accomplice and the serviceman was able to escape. He was unhurt but shaken.

Detectives are still keeping an open mind over the motive and a terrorist-related incident has not been ruled out.

Officers have said the attack would have required planning and other people may have been involved.

Earlier in the week, detectives said it was increasingly likely the men were part of a larger team.

Counter terrorism officers from the Metropolitan police are helping Norfolk officers with the inquiry.

Det Supt Durham said it is possible there was at least one other person in the car. He also said the bearded suspect was likely to have facial injuries.

“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,” he said.

House-to-house inquiries have also been carried out and officers are checking CCTV footage.

Anyone who recognises either of the suspects or has information should call police on 101 or the hot lines 0800 056 0154 or 0207 158 0011.

Officers have warned the men should not be approached. Police should be called on 999 immediately.