ISLAMABAD - Pakistani security forces have arrested a senior al Qaeda operative, Muhammad Ali Qasim Yaqub alias Abu Sohaib Al Makki, from the port city of Karachi believed to be operating a network of militants involved in attacks on Saudi diplomatic mission in Pakistan. According to preliminary investigations, Al Makki is a Yemeni national and has been working directly under al Qaeda leaders along Pak-Afghan border. According to ISPR report, the arrest of Al Makki is a major development in unravelling the al Qaeda network operating in the region. His arrest came a day after a Saudi Arabian diplomat was killed on his way to the Saudi Consulate in Karachi suggesting that he has been subjected to a revenge killing by a terrorist outfit. Agencies add: The arrest follows a US covert operation in Abbottabad near Islamabad on May 2 that killed Al-Qaeda leader Osama bin Laden, and comes a day after US senator John Kerry visited Pakistan to smooth a damaging row caused by the raid. Al Makki is apparently not on the list of internationally most-wanted Al-Qaeda operatives but the militarys statement mentioned his network was operating in the region. His arrest came a day after a Saudi Arabian diplomat was killed in a hail of bullets on his way to the Saudi consulate in Karachi. It was unclear how senior al Makki actually is. The US Embassy in Islamabad was unfamiliar with his name and he does not appear on any lists under the US Rewards for Justice programme. The military did not give details on al Makkis rank in al Qaeda or when he was arrested. A senior security official in Islamabad said al Makki was between 35 and 40 years old and had been living with his three children and wife for some time. He gave some information about movements of some people, the official said, referring to militants. We are evaluating that information and planning actions. Military sources added that al Makki came to Pakistan in 2001 and operated in the border area between Pakistan and Afghanistan. None of the information from the military could be independently corroborated or confirmed. He was hiding in a house right in the middle of the city, a senior security official said. The arrest was made after intelligence operations began in various cities after May 2. The intelligence operation is still on.