The political party of slain Pakistani opposition leader Benazir Bhutto is gathering in a small southestern town Saturday to hold its first rally since the former prime minister's assassination in December.

At least 2,000 policemen have been dispatched to the town of Thatta, where Ms. Bhutto's widower, Asif Ali Zardari, will address thousands of supporters of her Pakistan People's Party (PPP).  Portraits of the Ms. Bhutto are serving as a backdrop on the stage.

Ms. Bhutto was killed in the city of Rawalpindi as she was leaving an election rally.  Her death led to weeks of unrest in Pakistan and the postponement of parliamentary elections, now set for February 18.

An independent probe by Britain's Scotland Yard police force released Friday said she died from an injury caused by the force of a suicide bomb blast, and not an assassin's bullet.

Scotland Yard determined the blast caused Ms. Bhutto to hit her head on the top hatch of her vehicle, through which she was waving to supporters.  The report also concluded there was a single attacker who fired shots at the former leader and then blew himself up.

The PPP dismissed the report, and has called for the United Nations to conduct a probe into the perpetrators, sponsors and organizers of Ms. Bhutto's assassination.

President Pervez Musharraf invited Scotland Yard to help investigate Ms. Bhutto's death after some of her supporters charged the government was involved in the attack.

Separately Friday, police said three people were killed and at least seven others wounded in election-related violence in Sindh province.  Supporters of Ms. Bhutto's party clashed with members of the ruling Pakistan Muslim League in two separate incidents.