QUETTA: Frontier Corps (FC) and police launched a search operation in all sensitive prisons of Balochistan on Tuesday, a day after security forces foiled a bid to jailbreak over 100 militants from a prison in Karachi.

Bashir Bangulzai, the Inspector General (IG) Prisons Balochistan told Dawn.com that four prisons have been declared sensitive in the province. The prisons include district Jail Quetta, Mach and Khuzdar and Gaddani.

“Security has been tightened in and around all 11 prisons in Balochistan,” Bangulzai said.

FC and police have been searching cells and inmates in all sensitive prisons located in Balochistan province, plagued by an armed insurgency and growing sectarian violence.

The Balochistan prisons chief said the prisons currently accommodate more than 3,000 inmates in different locations across the province.

“Only Quetta and Mach jails are overcrowded,” he said, adding that in the rest of the prisons, the number of inmates is relatively low.

Sources in the provincial Home and Tribal Affairs department told Dawn.com that high profile prisoners were kept in district jail Quetta and central jail Mach due to security reasons.

To ensure any untoward incident, the Balochistan government has also deployed paramilitary FC personnel along with police and jail staff.

However, Bangulzai acknowledged that security around district jail Quetta was tightened following the jailbreak attempt in Karachi.

“We have put forces on high alert after the incident in Karachi,” he said.

Sindh Rangers announced on Monday that they had foiled a bid to break into Karachi Central Jail after they found an underground tunnel being built inside a house near the prison. The militants were aiming to build the tunnel to lead directly into the jail barracks where high-value targets were being held.

*Also read: Karachi central prison: A tinderbox of expanding militant networks

The central jail in Karachi has been a scene of explosions and other criminal activity in recent years with an attack on a Sindh High Court judge planned and partly executed from within the precincts of the prison.

Pakistan's ageing, overcrowded prisons have witnessed several breakouts in recent years.

A raid by heavily armed militants on a jail in Bannu last August freed nearly 250 prisoners, while almost 400 fled in a similar incident at a prison in Dera Ismail Khan in 2012.