A tribunal in Bangladesh has sentenced a senior leader of an Islamic party to death for his role in the kidnapping and killing of people during the country's independence war against Pakistan in 1971.

The verdict came in a packed courtroom in the capital, Dhaka, in the presence of the defendant Ali Ahsan Mojaheed, the secretary general of the Jamaat-e-Islami party. The tribunal found him guilty of kidnapping and killing a journalist, a music director and a number of other people.

Mojaheed faced seven charges including genocide, murder, conspiracy and complicity in atrocities during the war. He is accused of leading a notorious group that during the war kidnapped and killed many teachers, journalists and writers who supported the cause for independence.

The court said five charges were proven beyond doubt, while the prosecution failed to prove two other charges.

The defence lawyers said they would appeal against the verdict.

Two tribunals dealing with war crimes have already delivered five verdicts against three incumbent leaders of Jamaat-e-Islami and a former chief and another man expelled from the party. Jamaat-e-Islami and its leaders had openly campaigned against the creation of Bangladesh and are accused of forming citizens' brigades to help the Pakistani army in the battle against the fighters who fought for independence. Bangladesh became independent with the help of India on 16 December 1971 when the Pakistani army surrendered in Dhaka.

Bangladesh says the Pakistani army killed 3 million people and raped 200,000 women, while about 10 million people took shelter across the border in India during the war.

Jamaat-e-Islami condemned the verdict and enforced a day-long general strike across the country on Wednesday. No major violence was reported. The party indicated that it might extend the general strike to Thursday.

Protests over previous verdicts have turned deadly.

The government of the prime minister, Sheikh Hasina, formed the tribunal in 2010 amid criticism from the main opposition Bangladesh Nationalist party, led by the former prime minister Khaleda Zia. Zia has said the tribunal is meant to weaken the opposition. Jamaat-e-Islami is the main political ally of Zia's party, and shared two posts in the cabinet during Zia's latest premiership in 2001-06.

Hasina's government says it pledged before the 2008 election to prosecute those responsible for war crimes. A political alliance led by Hasina's Awami League party won the election with a two-thirds majority.