DHAKA, Bangladesh — Violent clashes between protesters and security forces erupted across Bangladesh on Thursday, leaving at least 44 people dead, after a special war crimes tribunal handed down a death sentence to an Islamic leader for crimes against humanity committed 42 years ago, during the country’s 1971 war of independence from Pakistan.
The verdict against Delawar Hossain Sayedee, a leader of Jamaat-e-Islami, an Islamist party, resonated across the country. It was celebrated by the hundreds of thousands of young protesters who have taken to the streets in recent weeks to condemn Jamaat and demand justice in the war crimes cases against other party leaders, insisting that those who were convicted be hanged.
“This verdict is a victory for the people,” declared Imran H. Sarkar, a blogger and an organizer of the protests, during a rally on Thursday afternoon.
But followers of Jamaat reacted with fury, saying the case brought against Mr. Sayedee and others was politically motivated and tainted by judicial irregularities. The police and witnesses said that of the 42 people killed in the unrest, six of them were policemen.
Jamaat leaders had called a nationwide strike on Thursday to protest the verdict, and by afternoon bloodshed had erupted across the country, as party workers fought with the police in the streets.
The protests for and against Jamaat have convulsed Bangladeshi politics, demonstrating that the country has still not healed from the bloody 1971 conflict, in which an estimated three million people were killed and thousands of women were raped. Before the war, Bangladesh was East Pakistan, separated from the rest of that country by a wide expanse of India. The war pitted Bangladeshi separatists against Pakistani soldiers and local collaborators, who were known then as the Razakar Bahini.
“As judges of this tribunal, we firmly hold and believe in the doctrine that ‘justice in the future cannot be achieved unless injustice of the past is addressed,’ ” Justice A. T. M. Fazle Kabir commented in a written summary of the judgment.
The war crimes tribunal has convicted three Jamaat leaders in connection with the war, and other cases are under way, including some against defendants not affiliated with the party.
Mr. Sayedee, 73, is a well-known religious speaker with a bright red beard who became a member of the Bangladeshi Parliament after the war. Prosecutors accused him of involvement in looting and burning villages, raping women and forcing members of religious minorities to convert to Islam during the war.
His defense lawyer, Abdur Razzaq, scoffed at the court’s verdict and accused the authorities of deliberately prejudicing the trial and preventing an important witness from testifying.
“This is unfortunate, and this is unexpected,” Mr. Razzaq said of the verdict and sentence in a telephone interview. “This is a perverse judgment. It is inconceivable that a court of law awarded him a conviction. This prosecution was for a political purpose.”
Jamaat leaders and other opposition politicians have said for months that the government was manipulating the war crimes process to go after political rivals, accusations that the authorities deny. The proceedings have already created dissent and some international criticism. The chief presiding judge resigned after reports, based on hacked Skype conversations, that the judge had improper contacts with a legal expert linked to prosecutors and the government.
But to many Bangladeshis, the real injustice has been that war criminals have remained free for decades. On Feb. 5, the tribunal convicted another Jamaat leader, Abdul Quader Mollah, and sentenced him to life in prison. Furious that the tribunal had not sentenced Mr. Mollah to death, protesters gathered in growing numbers, surpassing 200,000 on some days.
The protests have become known as the Shahbagh movement, named for a large intersection in central Dhaka where the main demonstrations have taken place. Many political analysts say the Shahbagh protests are the most significant spontaneous political movement in Bangladesh in decades. Though the movement may be suffused with idealism and proud nationalism, it also bears a hard edge, with demands for the execution of convicted war criminals.
Sultana Kamal, a prominent human rights leader in Dhaka, said that she disagreed with the calls for the death penalty, but that they reflected the cynicism of Bangladeshis who have seen war criminals evade punishment for decades. Many people were infuriated when Mr. Mollah flashed a victory sign after receiving his life sentence.
“We have a problem in accepting that they are demanding the death penalty,” Ms. Kamal said in a telephone interview. “But we understand that it was from a nervousness among the people here that unless they are given the highest penalty in the land, these people will come back out.”