ISLAMABAD: Al Qaeda operative Mohammed Ali Qasim, alias Abu Sohaib al-Makki, who was recently arrested in Pakistan, had been living in the country for almost 10 years and was involved in recent terrorist activities in Karachi.

Makki’s arrest, according to a senior security official, yielded a ‘treasure trove’ of information. He is said to be an expert in computers and explosives.

It’s not clear when Makki, 34, started living in Karachi with his family.

The exact date of arrest is being kept secret because security agencies are working to unearth his “elaborate terror network” in the city.

It has been claimed that Makki was arrested days after Osama bin Laden had been killed in Abbotabad. But others said he had been under surveillance since the beginning of this month, but was arrested on Tuesday.

Before moving to Karachi, the terrorist of Yemeni origin lived in South Waziristan, NorthWaziristan, Peshawar and Faisalabad.

Makki had been in Pakistan since June 2001. He was taken into custody along with his wife and three children. Initial investigations revealed that he who earlier operated along the Pak-Afghan border facilitating movements of Al Qaeda operatives. He later started targeting Pakistan and got involved in terrorist activities in Karachi, including bombings and probably target killings.

It is not clear if he had something to do with the planning of the grenade attack on the Saudi Consulate and subsequent killing of Saudi diplomat Hassan al-Qahtani, who is thought to have been working on Saudi dissidents and extremists living in Pakistan.

Although, security officials dismissed as speculative reports that he was acting as a courier between Osama bin Laden and Ayman Zawahiri, they admitted that he had been in touch with Al Qaeda’s top leadership and one of the sources described him as a linchpin for the terror organisation.

Pakistan and the US had on Monday under their `renewed terms of engagement’ agreed to undertake joint actions against Al Qaeda elements in Pakistan.

A source said that under the arrangement if Pakistan were to go after any Al Qaeda operative it would share information with the US. It is expected that Pakistani officials would share detailed information with the US when CIA Deputy Director Mark Morrell visits Islamabad shortly.

The CIA official is expected to come for follow-up talks after Senator Kerry helped ease some of the tensions in the aftermath of the Abbottabad raid.

Reuters adds: Makki was a ‘mid-level’ operative and explosives expert involved in plotting attacks in Pakistan and Afghanistan, according to security officials.    “He is a mid-level operative and has been very active in the region, but I can’t say yet if he is ‘huge’ in the global scheme of things,” said the official, adding that intelligence agencies had arrested him about a week ago in Karachi.

“Nonetheless, he is a very good catch.”

There was no immediate way of verifying Makki’s rank within Al Qaeda.

A military official in Islamabad said Makki was an ‘explosives expert’. The official said he was ‘definitely’ linked to the Al Qaeda leadership but did not elaborate.

“He is still being interrogated and we hope to get more information from him,” said the official.

A senior security official in Islamabad said that Makki was between 35 and 40 years old and had been living with his three children and wife “for some time”.

“The whole Osama issue has been very embarrassing for us, and that is why we have significantly stepped up efforts to capture any militants that may be hiding here,” said another military official.

“We have always been very serious on terrorism, but now we are moving against militants even more seriously. You will hopefully see more results soon.”