Bangladesh's war crimes court has postponed a verdict on the leader of the country's largest Islamist party for alleged crimes committed during the 1971 independence struggle, according to local media.

Motiur Rahman Nizami, 71, faces 16 charges including mass killings, rape, arson and genocide, relating to violence committed by a militia.

The court deferred the verdict after prison authorities informed the International Crimes Tribunal that Nizami was sick, the Daily Star newspaper reported.

The head of a three-judge panel, M Enayetur Rahim, said a new date for the verdict will not be set until the judges see a detailed medical report on Nizami.

Thousands of extra security officials were deployed across the country ahead of the verdict.

Jamaat leaders convicted last year Ghulam Azam - ex-Jamaat chief sentenced to 90 years in jail. The following leaders were sentenced to death: Delwar Hossain Sayeedi

Ali Ahsan Mohammad Mujahid

Salahuddin Quader Chowdhury

Muhammad Kamaruzzaman

Abdul Kader Mullah

Abul Kalam Azad

Similar verdicts last year, which included the execution of a senior Jamaat leader, sparked nationwide protests in which 200 people were killed.

Nizami, the president of Jamaat-e-Islami, pleaded not guilty and accuses the country's secular government of using the special war crimes court to target opposition leaders.

Prosecutors said Nizami was one of the chief architects of the mass killings of Bengalis in the 1971 independence war against Pakistan.

The government says three million people died in the war. Independent researchers put the estimate between 300,000 and 500,000.

"He established the al-Badr forces during the war to support the Pakistani army," prosecutor Mohammad Ali told the AFP news agency.

As the head of al-Badr, he was involved "in committing crimes against humanity such as genocide, murder, rape and arson" as well as the murder of some of the country's top intellectuals, Ali said.

Nizami, a minister in the Islamist-allied government between 2001-06, is already on death row for trying to traffic weapons to a rebel group in northeast India.

In total, 11 top opposition figures - nine from Jamaat and two from the main opposition Bangladesh Nationalist Party - stand accused of war crimes.

Rights groups say the war crimes court falls short of international standards.

The latest verdict would be the first since the prime minister, Sheikh Hasina, won a general election in January, which was marred by widespread fraud and a boycott by all opposition parties.

Jamaat was banned from participating.