AFP/ Dhaka

Bangladesh's highest court Tuesday upheld the death sentence against a top Islamist leader for war crimes during the country's battle for independence, prompting his opposition party to call a general strike in protest.

Ali Ahsan Mohammad Mujahid could now be hanged within months after the Supreme Court dismissed his appeal against the sentence for the murder of scores of intellectuals during the 1971 conflict.

The 67-year-old is one of about a dozen leaders of Bangladesh's largest Islamist party, Jamaat-e-Islami, a key opposition group, convicted by a controversial war crimes tribunal set up by the secular government in 2010.

The convictions have triggered the country's deadliest violence since independence with some 500 people killed, mainly in clashes between Jamaat activists and police.

Security was tight ahead of Tuesday's ruling, with heavily armed police and border guards surrounding the court in Dhaka and patrolling nearby streets.

But widespread violence was unlikely following a recent crackdown against the opposition by Prime Minister Sheikh Hasina's government.

Jamaat, thousands of whose supporters have been arrested in the crackdown, called the strike for Wednesday, branding the trial of its general secretary "farcical".

"Mujahid is a victim of the government's conspiracy," Jamaat's acting chief Moqbul Ahmed said in a statement.

Mujahid was found guilty in 2013 of leading Al Badr, a notorious pro-Pakistani militia that carried out "exterminations" of Bangladeshi intellectuals including top writers, journalists and professors towards the end of the nine-month war.

Prosecutors said Mujahid now faces the gallows within months unless his case is reviewed by the same court or he is granted clemency by the president.

"Souls of the war martyrs can finally now rest in peace after today's verdict," prosecutor Mokhlesur Rahman Badal told AFP outside the court.

The court has swiftly dismissed previous reviews of two other senior Jamaat officials on death row, leading to their execution, the latest in April this year.

Those leaders also declined to seek clemency from the president, saying they did not recognise Hasina's government.

- Bodies found dumped -When it became clear that Pakistan was losing the war, dozens of intellectuals were abducted from their homes and murdered in December 1971 in the most gruesome chapter of the conflict.

Their bodies were found blindfolded with their hands tied and dumped in a marsh on the outskirts of the capital.

Defence lawyers have said Mujahid's name was not in the list of Al Badr commanders or activists that was published by the post-independence government.  

"We'll seek a review of the Supreme Court judgement," lawyer Shishir Manir told AFP.

The ruling is a blow to the beleaguered opposition, thousands of whose leaders and supporters have been detained as part of the government's crackdown in recent months.

The government has been attempting to end an opposition campaign to force Hasina to resign and call fresh elections. The campaign has left scores dead mainly in fire bomb attacks by opposition activists.

The trials have divided the country with the opposition and Jamaat branding them a sham aimed at eliminating their leaders rather than meting out justice. Secularists have demanded the execution of all those accused.

Mujahid was a senior minister from 2001-2006 in a previous government led by then prime minister Khaleda Zia. He was an influential leader in the opposition alliance until his arrest in 2011.  

International rights groups, legal experts and the opposition have criticised the tribunal, saying its procedures fall short of international standards.

Hasina has rejected any criticism of the International Crimes Tribunal's trials, saying they were needed to heal the wounds of the war. Bangladesh says three million people died but independent estimates put the toll much lower.