* Jamaat fought against independence in 1971
* Crowds cheer verdict, but Islamists protest
* Rights groups have criticised tribunal process (Adds violence, general strike, edits)
By Ruma Paul
DHAKA, May 9 (Reuters) - A Bangladesh tribunal convicted and sentenced an Islamist party leader to death on Thursday for atrocities in the country's war of independence, bringing a wave of violent protest from his supporters nationwide.
Mohammad Kamaruzzaman, 61, assistant secretary general of the Jamaat-e-Islami party, was found guilty of genocide and torture of unarmed civilians during the 1971 war to break away from Pakistan, lawyers and tribunal officials said.
War veterans were among hundreds on the street outside the court who cheered the verdict, the fourth war crimes conviction by the tribunal. More are expected.
Bangladesh is reeling from a garment factory collapse that killed more than 900 people last month and has also been rocked by protests and counter-protests related to the complex legacy of the independence war in recent months.
The unrest is one of the main challenges facing the government of Prime Minister Sheikh Hasina, who opened an inquiry into abuses committed during the war in 2010.
Leading defence lawyer Abdur Razzaq rejected the verdict and sentence and said Kamaruzzaman would appeal.
Supporters and activists of Jamaat and its student front Islami Chatra Shibir staged violent protests against the verdict in cities across the country, including Sylhet, Rajshahi, Khulna and Patuakhali, police and witnesses said.
They said activists blocked highways, attacked vehicles, started fires and attacked banks and government buildings. Police used tear gas and rubber bullets to disperse them.
Jamaat called a day-long general strike on Sunday to protest against the verdict.
At the end of British colonial rule of India in 1947, the territory of what is now Bangladesh became East Pakistan, politically united with West Pakistan but separated from it by hundreds of kilometres (miles) of Indian land.
It won independence with India's help in December 1971 following a nine-month war against West Pakistan.
In the fighting, Jamaat opposed independence and fought alongside the West Pakistan military. They were accused of involvement in atrocities.
Unrest erupted in January when the tribunal sentenced to death in absentia a leader of Jamaat. Thousands took to the streets in February demanding the execution of another Jamaat leader after he was jailed for life on similar charges.
More than 100 people have been killed in clashes this year, most of them Islamist party activists and members of the security forces.
"We are happy with the verdict as it fulfils the demands of the countrymen, especially the young generation," said Imran Sarker, who gave up his medical practice to lead the movement demanding the death penalty for all war criminals.
Jamaat and the main opposition Bangladesh Nationalist Party accuse the prime minister of using the tribunal to persecute them. The government denies the charge.
The tribunal has been criticised by rights groups for failing to adhere to international standards. Human Rights Watch said lawyers, witnesses and investigators reported they had been threatened. (Additional reporting by Serajul Quadir; Editing by Andrew Roche)