Akhtar Zaman, the Sindh interior minister, said the toll covered the period from 6pm on Thursday when violence first erupted as word spread of Bhutto's killing.
 
He said his forces anticipated the situation might get worse after her funeral in Larkana in Sindh on Friday afternoon.

Politician killed
 
A remote-controlled bomb also killed four people, including a politician from a party backing Pervez Musharraf, the president, in Swat valley in the northwest of the country on Friday, police said.
 
In Islamabad, the capital, about 100 protesters burned tyres in a commercial area of the city.

Ten railway stations and several trains across Sindh were also burned.
 
This forced the suspension of all train services between Karachi, the capital of Sindh, and the province of Punjab, according to Mir Mohammed Khaskheli, a senior rail road official.

Khaskheli also said one section of the track leading to the border with India was uprooted.

Shoot on sight

The government has ordered paramilitary forces, or rangers, to shoot on sight those engaged in the disturbances in Karachi.

Major Athar Ali, a spokesman for the force, said: "Paramilitary rangers have been given orders to shoot on sight if they see miscreants indulging in anti-state activities, attacking government property or setting on fire private property."

Violence has engulfed several Pakistani
provinces of following the killing [Reuters]
The force reportedly includes 16,000 rangers deployed across Sindh, with 10,000 in Karachi alone.

Troops were also sent to the cities of Larkana, Sukkur, Shahdad Kot and Rohri in Sindh.

Major-General Waheed Arshad, a Pakistani military spokesman, said: "Troops have been pre-positioned in these cities.

"Troops will remain present in these cities and assist local authorities in case of any eventuality."

In Peshawar, the main city of the North West Frontier Province, about 4,000 supporters of Bhutto's Pakistan People's Party demonstrated on Friday.
 
Several hundred also ransacked the office of a party allied Musharraf, burning furniture and stationery.

Murder mystery

Musharraf has blamed Bhutto's killing on pro-Taliban fighters based along the border region with Afghanistan, pledging in a televised speech that "we will not rest until we eliminate these terrorists and root them out".

Bhutto was killed by a bomber on Thursday
after a party rally in Rawalpindi [Reuters]
But authorities said they had yet to identify the attacker.

Saud Aziz, the chief of police in Rawalpindi, said: "It is too early to say who may have been responsible."

Aziz said that a joint task force of police and officials from other law-enforcement agencies were investigating the case. 

But doubt has been cast by several commentators on the possibility of the culprits ever being apprehended.
 
"Television images soon after Bhutto's assassination showed fire engines hosing down the crime scene, in what can only be considered a calculated washing away of forensic evidence," Hussain Haqqani, a Pakistan analyst, wrote on Friday.