May 27 (Bloomberg) -- A suicide bombing at a Muslim shrine in Pakistan's capital, Islamabad, today killed at least 50 people, according to an ambulance service called to the scene.

Another 200 people were injured by the blast inside the Bari Imam shrine in the east of the city, the ambulance service, the Edhi Welfare Trust Group, said in an e-mailed statement. The bomber was 20 to 25 years old, the organization said without providing further details. Police estimated that 19 were killed and more than 100 hurt, according to duty officer Naseer Khan.

The shrine is behind the home of Prime Minister Shaukat Aziz. The bomb exploded at about 11:15 a.m. local time as hundreds of worshippers marked the anniversary of the death of Shah Abdul Latif, a spiritual leader buried there, Khan said in a telephone interview from Islamabad. There were no reports of casualties at Aziz's house.

The Islamic republic has had several bombings in recent years, blamed by the government on opponents of President Pervez Musharraf's support for the U.S.-led campaign against terrorism. Some of the attacks are attributed to rivalries between the Shiite Muslim minority and the Sunni Muslim majority.

Tighter Security

Security was tightened in Karachi, especially at the port city's Shiite mosques, after the blast in the capital and in anticipation of protests across the country over the treatment of the Koran at Guantanamo Bay, Karachi police inspector Tariq Jamil said in a telephone interview. Muslims worldwide have expressed anger at allegations that guards at the U.S. prison in Cuba mistreated Islam's holy book in front of Muslim inmates.

The Bari Imam shrine has been a focus of the Shiite-Sunni rift, Information Minister Sheikh Rashid Ahmed said. There was no information on whether there was a sectarian motive in today's attack. In February, the shrine's custodian, Raja Akram, was killed by unknown assailants, Ahmed told GEO television.

In October, 36 people were killed in a car-bomb attack on a Sunni Muslim congregation in Multan, in Pakistan's eastern Punjab province. A bombing of a Shiite mosque in Sialkot, in Punjab province, earlier that month killed 19 people.

To contact the reporters on this story: Khalid Qayum in Islamabad at kqayum@bloomberg.net; Haris Zamir in Karachi, Pakistan at hzamir@bloomberg.net.

Last Updated: May 27, 2005 10:37 EDT