A Bangladesh tribunal sentenced Jamaat-e-Islami party leader Abdul Quader Mollah to life in prison today for his role during the independence war against Pakistan in 1971.
The High Court in Dhaka said the head of the country's main Islamic party was guilty of charges including murder, rape, torture and arson.
Jamaat had already ordered a nationwide general strike to denounce the trial, shutting down schools and shops and halting most traffic in Dhaka.
Jamaat supporters exploded homemade bombs and clashed with police in parts of the capital, leaving several people injured.
One person was killed as protesters clashed with police after the verdict was announced and Jamaat said it would extend its strike to tomorrow.
Mr Mollah and five other leaders of the party have been on trial before Dhaka's International Crimes Tribunal.
They have been accused of committing atrocities during the nine-month war against Pakistan more than 40 years ago.
Former party member Abul Kalam Azad was sentenced to death last month.
The government of Prime Minister Sheikh Hasina initiated the process of trying those accused of committing crimes against humanity in 2010.
Jamaat - a key partner in a former Bangladeshi government - claims that the charges are politically motivated.
Though the sentence was the most serious the tribunal could have issued short of execution, a government official expressed disappointment.
"It did not reflect the people's expectation. We are frustrated," junior Law Minister Qamrul Islam said.
And hundreds of veterans gathered outside the court demanding the Islamist leader be put to death.
Until the independence war in 1971, Bangladesh was the eastern wing of Pakistan.
Jamaat campaigned against independence and has been accused of forming several groups to collaborate with Pakistani troops in killing, rape and arson.
The government says that Pakistani troops, aided by local sympathisers, killed 3 million people and raped 200,000 women.
Mr Mollah was tried on six counts, including playing a role in the killing of 381 unarmed civilians.
He denied the charges and defence lawyer Abdur Razzaq said he will appeal against the sentence.
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