QUETTA: Security forces arrested three suspects involved in an attack at Karachi naval dockyard from the Lak Pass area of Quetta the other day, a security official said.

A security official, who requested anonymity, told Dawn.com that acting on intelligence reports, security forces conducted raids in the outskirts of Quetta and picked up three suspects.

"The suspects are Navy officials," he added, giving no details about their ranks.

They were shifted to Karachi on a plane from Quetta for further interrogation.

The suspects were trying to escape to Afghanistan, when they were intercepted by security forces.

He said some suspects were also apprehended by security forces from Ormara and Karachi after the initial interrogation.

The Tehreek-i-Taliban Pakistan (TTP) have already claimed responsibility for the attack on the naval dockyard, claiming they had inside help.

Defence Minister Khawaja Asif has on record said “some of the navy staff of commissioned ranks and some outsiders” were involved in the terrorist strike.

Militants attacked the naval dockyard in a raid which left an officer and two insurgents dead.

The Taliban have already threatened a bloody response to a military offensive against insurgents in North Waziristan on the Afghan border.

The military launched the offensive in mid-June shortly after a brazen attack on Karachi airport that left dozens dead and extinguished a largely fruitless peace process with the TTP.

The weekend raid was the latest in a series of high-profile attacks on key installations by the Taliban in recent years, including an 2011 assault on a naval base, also in Karachi, and on the military's headquarters in 2009.

New al Qaeda South Asia arm claims Karachi attack

A copy of a pamphlet, apparently issued by the al Qaeda's new South Asia chapter, which was available with Dawn claimed responsibility for the Karachi naval yard attack.

The group also claimed naval officers had helped in the attack and that several of its members were deserters from the armed forces which were subordinate tot the United States.

If true, it would be the first attack claimed by the terror network's new wing, whose creation was announced by chief Ayman Al-Zawahiri last week.

The operation near Karachi shore was an attack by al Qaeda in the Subcontinent,” an Urdu-language statement from the alleged group said.

Al Qaeda claims they were planning to attack the US fleet after taking over PNS Zulfiqar on the Navy dockyard in Karachi.

The pamphlet said that the group's fighters were 'assigned the mission of taking over PNS Zulfiqar and use its missile systems to target a US fleet.'

It was not immediately possible to confirm which US fleet was the target of the attack.

The group also claimed that its fighters had taken over the ship and were heading towards the target when their fighters were killed or arrested by security forces.

There was no official comment over the claims of responsibility made by the TTP and al Qaeda. Militant groups in the region often exaggerate claims about attacks.