Leaders of Ms. Bhutto's Pakistan People's Party held an emergency meeting in the capital of Islamabad to plot their course of action in protesting Ms. Bhutto's five-year prison sentence.
They were expected to call for widespread demonstrations, perhaps after Ms. Bhutto returns to Pakistan sometime next week.
In her hometown of Karachi on the Arabian Sea coast, 1,500 of Ms. Bhutto's supporters marched through the streets, setting fire to effigies of Nawaz Sharif, Pakistan's prime minister and Harvard-educated Ms. Bhutto's archenemy.
They shouted slogans condemning the government and vowed to support their embattled leader, who was also fined $8.6 million and banned from politics by a Pakistani court on Thursday. The court also ordered her properties confiscated.
Smaller demonstrations took place in Islamabad, Rawalpindi and in Lahore, Sharif's hometown.
"The charges against me were based from the outset on fabricated charges and forged documents created by the Nawaz regime to politically frame me and ultimately undermine the Pakistan People's Party," Ms. Bhutto said in a statement from London.
Ms. Bhutto, heir to an Asian political dynasty and Pakistan's first woman prime minister, has asked international human rights groups to study the documents.
"Nawaz Sharif shall not succeed in creating a dictatorship in Pakistan," she said.
Charges of corruption and abuse of power have dogged Ms. Bhutto for much of her political career.
Both her first and second terms in office were brought to a sudden halt when her governments were dismissed on charges of runaway corruption and misuse of power. She has steadfastly maintained her innocence.
Her last government was dismissed in 1996. Sharif came to power in general elections held in February 1997. Her first government was dismissed in August 1990 after only 20 months in power.
Sharif, too, has been tagged with charges of widespread corruption, and Ms. Bhutto has filed several charges of graft against the prime minister, his family members and colleagues.
In Pakistan's rough and tumble politics, corruption has become endemic.
It's not immediately clear whether Ms. Bhutto will be arrested when she returns to Pakistan.
Her lawyers in Islamabad say it's unlikely because they will appeal her conviction. Under Pakistani law, the sentence is stayed while an appeal is being heard, said Iftikar Gailani, a senior party official and prominent lawyer.
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