The bureau focuses on the country's fight against al-Qaeda and homegrown armed groups tied to Osama bin Laden's network. 'Death threats'
"The two officials were in the forefront of anti-al-Qaeda operations in Karachi. They were involved in the arrests of many of the terror network's operatives in the past two months," a senior intelligence official told the AFP news agency.
"They received death threats from the Taliban and al-Qaeda. Aware of these threats the authorities posted Inspector Ibrahim out of the country and he was to take up this post," the official said.
The Intelligence Bureau is one of three Pakistani intelligence agencies, but it is the only one that is controlled by the interior ministry.
The Military Intelligence and Inter-Services Intelligence (ISI) are tied to the armed forces.
Police recently arrested a figure linked to al-Qaeda in Karachi, Pakistan's largest city, who was wanted for two bombings after a shootout in January that left four people dead. Qasim Toori was a member of the banned Sunni Muslim group Jundullah (Army of God).
Karachi was the scene of Pakistan's deadliest ever suicide attack in October last year when two bombers attacked the homecoming procession of Benazir Bhutto, the now assassinated former prime minister. At least 139 people were killed in the attack.
Violence in Pakistan has intensified since last July when the army stormed a mosque in Islamabad, the Pakistani capital, to crush an armed student movement.
About 600 people have been killed since the start of this year alone.
At least 21 people were killed after a suicide bomber struck the office of the Federal Investigation Agency (FIA) in the eastern city of Lahore early this month.