Chief Justice Surendra Kumar Sinha announced the apex court's verdict to dismiss the appeal of Jamaat-e-Islami stalwart and media tycoon Mir Quasem Ali, who was convicted of murder and abduction during Bangladesh's liberation war.
"The sentence (death penalty) is maintained," Sinha announced in a crowded courtroom.
The decision of the five-member bench of the top court came 16 months after the country's International Crimes Tribunal (ICT) sentenced 63-year-old Ali to death for atrocities committed during the liberation war in 1971. He had challenged the verdict.
He was convicted of running a militia torture cell, Al Badr, that carried out killings of several people.
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The court found as valid most of the charges against him, including carrying out murders and tortures siding with the Pakistani troops in line with the policy of Jamaat, which was opposed to Bangladesh's 1971 independence.
Ali headed a media corporation aligned with Jamaat before his arrest in 2012.
He was the Al Badr's third most important functionary after Jamaat-e-Islami chief Motiur Rahman Nizami and Secretary General Ali Ahsan Mohammad Mujahid.
Officially, three million people were killed by the Pakistani army and their Bengali-speaking collaborators during the 1971 liberation war.
Ali faces the gallows within months unless his case is reviewed by the same court or he is granted clemency by the president.
Three senior Jamaat officials and a leader of the main opposition party have been executed since December 2013 for war crimes.
A war crimes tribunal set up in 2010 has sparked violence and drawn criticism from opposition politicians who said it is victimising Prime Minister Sheikh Hasina's political opponents.