Chandigarh, Jan. 22: Three prisoners being tried for the assassination of Punjab chief minister Beant Singh have pulled off an audacious jailbreak, burrowing their way up to the boundary wall and scaling it to reach a getaway vehicle lying in wait.

The escape from the high-security Burail jail was carried out last night amid rain and extreme cold. Another prisoner who is involved in a separate case also slipped out with the trio.

Beant Singh was killed by a human bomb as he was stepping into his car outside the Punjab secretariat here on August 31, 1995. The bomb, allegedly carried by Babbar Khalsa member Dilawar Singh, killed 14 others on the spot. Three more succumbed to injuries later.

Three of the accused in the assassination case — Jagtar Singh Tara, Jagtar Singh Hawara and Paramjit Singh Bheora — escaped by digging a tunnel 14-feet deep and 94-feet long and scaling the 15-feet-high boundary wall.

Tara, Hawara and Bheora were provided the fourth fugitive, Dev Singh, as a “helper” since they were not allowed to mix with other jail inmates due to security reasons.

The trio, with a record of botched escape attempts, had spread terror among jail staff and fellow prisoners and had been provided VIP facilities in their cells, police said.

“We are looking at all angles to the escape, including connivance of jail personnel,” Lalit Sharma, adviser to Chandigarh administrator Justice (retd) .P. Verma, said.

The Union territory administration has arrested five persons, including deputy jail superintendent D.S. Sandhu, havaldar Nishan Singh and havaldar Kashmir Singh, who was in charge of barracks no. 7 where the trio was lodged. CRPF constables Inder Singh and Jagir Singh were also arrested.

The police have mounted one of the biggest manhunts in recent times, spread over several states. Barricades have been set up at all major entry and exit points in Jammu and Kashmir, Haryana, Punjab, Himachal Pradesh and areas bordering Rajasthan and Delhi.

The police said the prisoners could not have dug the tunnel in a day. “It is a long tunnel and must have taken days of planning. Moreover, we are looking at where the huge amount of earth had been deposited while the tunnel was being made. We are also screening records of people who may have met the prisoners during the last six months,” a senior Punjab police officer said.

Burail jail has been barricaded and no one is being allowed inside. Located on the outskirts of Chandigarh and near the satellite town of Mohali, the jail is home to many extremists.

Officials are tight-lipped on the presence of Kashmiri militants in the jail, but some arrested when terrorism was rife in Punjab are said to have “strong” links with insurgents in Jammu and Kashmir.

The absence of the prisoners was noticed during the daily headcount at 7 am today. A search in the barracks showed up the tunnel with its mouth 20 metres from the boundary wall. The stretch from the barracks to the inner wall is patrolled throughout the day. The area between the outer wall and the boundary wall is not heavily patrolled, making it easy to escape.

The prisoners escaped from the tunnel whose mouth is just 10 metres from a watch tower, which was not manned last night. The prisoners also had to crawl in the open for over 70 metres before escaping in a vehicle — tyre marks have been detected on the wasteland near the right side of the jail. The police were informed only at 8.15 am.

This was the third jailbreak attempt by the prisoners — in 1998 they made two abortive bids to flee the jail, first by trying to smuggle in RDX in sweets, and later by trying to seize the then jail superintendent and make a dash for freedom.

Amar Singh Chahal, counsel for the accused, said the escape was stage-managed so that they could be “eliminated”. “Why should they try to escape? They will get caught sooner or later and that would ensure a stricter sentence for them,” he said.

The Beant Singh trial involving 13 accused was being held on the jail premises.