KARACHI: A coordinated assault on a police compound far from Taliban and al Qaeda heartlands along the Afghan border showed the ability of militants to strike back despite being hit by US drone strikes and Pakistani army operations.

The Pakistani Taliban claimed responsibility for Thursday night's attack in downtown Karachi, the country's largest city and commercial hub, according to media reports.

Seventeen people were killed and more than 100 were injured in one of the first coordinated strikes against a state target in the city.

The Pakistani Taliban is believed to be allied with the al Qaeda and has emerged as the most potent threat to the stability of the country since 2007. Its suicide squads have killed thousands of people in attacks on government, security forces and civilians.

''These attacks which are happening around the country, they are carried out by enemies of the nation,'' said Faisal Mehmood, a resident of Karachi, said Friday.

The gang of around six gunmen managed to penetrate a high-security area of Karachi that is home to the US Consulate, two luxury hotels and the offices of regional leaders. They opened fire on the offices of the Crime Investigation Department before detonating a huge car bomb that levelled the building and others nearby.

The police offices housed a detention facility that was believed to be holding criminals. There were conflicting accounts over whether militants were also being held there.

The CID takes the lead in hunting down terrorists in Karachi. Earlier this week, the agency arrested six members of Lashkar-i-Jhangvi, a militant group allegedly allied with the al-Qaeda and blamed for several high profile attacks in recent years. The suspects were presented before a court earlier Thursday.

Militants are known to have found shelter among Karachi's 18 million people, and there have been occasional attacks on Shia Muslims as well a blast last month at a Sufi shrine.

But the city had largely escaped a wave of violence last year that saw many attacks in Lahore, Peshawar and other cities.

The government has declared war on the militants, and the army has moved into several areas in the northwest close to Afghanistan. The United States has increased the tempo of missile strikes in the region over the last two months, with close to 100 this year alone.

But the Pakistani state still allegedly distinguishes between militants who attack inside Pakistan and those who focus on fighting US troops in Afghanistan or Indian rule in the disputed Kashmir region, believing the latter to be ''good'' militants. Critics say this policy is short-sighted, noting that groups are increasingly coalescing and support each other.