The three main intelligence agencies in Pakistan are ISI, Military Intelligence [MI] and the Intelligence Bureau [IB]. Each agency has its own specific responsibilities, but all share the common goal of preserving Paksitan's national security. Since any significant domestic or foreign political activity impinges on national security, there has traditinally been considerable overlap in the activities of these three agencies. The ISI and MI have generally focused on matters of immediate military interest, and the IB concentrated on domestic political activities.Prior to the imposition of Martial Law in 1958, the IB reported directly to the Prime Minister and the two military agencies to the Commander-in-Chief of the Army (C-in-C). When martial Law was promulgated in 1958 all the intelligence agencies fell under the direct control of the President and Chief Martial Law Administrator, and the three intelligence agencies began competing to demonstrate their loyalty to Ayub Khan and his government.
The Intelligence Bureau monitors politicians, political activists, suspected terrorists, and suspected foreign intelligence agents.The IB keeps tabs on political operatives from countries it considers hostile to Pakistan's interests, and it is responsible for harassing domestic opposition parties. Credible reports indicate that the authorities commonly resort to wiretapping and occasionally intercept and open mail.
The Intelligence Bureau is under the Prime Minister's cabinet division. A total of Rs. 25.8 million was spent on the IB in 1976-77. The Intelligence Bureau grew in importance with the re-election of Benazir Bhutto in 1993. One of her most controversial appointments to government posts was that of Masood Sharif as Director General Intelligence Bureau. Sharif was believed to have played an active role in toppling the Shabir Shah government in the North West Frontier Province (NWFP). His appointment precipitated a major crisis in the Pakistani state apparatus, because Benazir then began using the IB chief to erode the once all powerful ISI's base. Benazir's attempts to root out the influence of military intelligence in the country's internal affairs mirrored the failed efforts of her father in the 1970s. This was the last straw as far as the military was concerned.
In his order dismissing Prime Minister Bhutto on 05 November 1996, President Leghari accused the Government of massive illegal wiretapping, including the telephone conversations of judges, political party leaders, and military and civilian officials. One of the first acts of President Leghari after dismissing Benazir was to imprison Masood Sharif, head of Intelligence Bureau under Prime Minister Benazir Bhutto. He was arrested and imprisoned, not on corruption charges but as part of a murder investigation.
On 15 December 1996, the caretaker government announced that effective immediately all foreign and domestic mail was to be subject to censorship by the Special Branch and the Intelligence Bureau.