ISLAMABAD: Authorities have arrested a man they describe as an important commander in Al Qaeda's newly created South Asian wing, police said on Friday.

Police arrested Shahid Usman, in his mid-thirties, and four others in Karachi late on Thursday. They also seized weapons and 10kg of explosives.

Al Qaeda's new South Asia wing, Al Qaeda in the Indian Subcontinent, tried to hijack a Pakistani navy ship in September this year, a few days after the group had announced its formation.

Police say Usman is the head of the Al Qaeda wing in Karachi, a steamy port city of 18 million people, and was planning more attacks there.

Read: Top Al Qaeda leader killed in South Waziristan

“He is the Karachi chief of Al Qaeda's newly formed wing working under the set up of Asim Umar, the South Asia chief of Al Qaeda,” a senior official at the police counter-terrorism unit said.

The official said Usman lived in Defence, a wealthy neighbourhood, and owned a car-parts dealership in one of the city's most expensive commercial areas. “Unlike the usual militant profile, Usman comes from an affluent background,” the police officer said.

Officials said Usman was previously associated with the outlawed Harkatul Jihad-al-Islami militant group, whose operational commander, Ilyas Kashmiri, was killed in a US drone strike in 2011 near the Afghan border. Usman had received training in Afghanistan, the police officer said.

Read: Al Qaeda leader Umar Farooq killed in N Waziristan drone strike

The suspected terrorists were arrested from Lakri Gali, Old Haji Camp neighbourhood of the city, a police statement said, adding that the arrested men “operate Al-Qaeda's network in the city” and were behind several “acts of terrorism”.

Al Qaeda announced the formation of its South Asian wing on Sept 4 with Al Qaeda chief Ayman al-Zawahiri promising to spread a holy war across South Asia, home to more than 400 million Muslims.

Analysts say the move is part of Al Qaeda's plan to take advantage of the planned withdrawal of US-led forces from Afghanistan and boost its influence in the region.

The new Al Qaeda wing may also be an attempt to grab back the initiative from the Islamic State (IS) militant group that was expelled from Al Qaeda for its brutal tactics and which now holds parts of Iraq and Syria. Pakistani militants say envoys from the IS are trying to make contacts in the region.

Usman's arrest followed the reported killing of two senior Al Qaeda leaders in Pakistan this month.