Bangladesh has executed a senior Islamist party official convicted of crimes against humanity during the country's 1971 independence war against Pakistan.

A prison official said Mohammad Qamaruzzaman was hanged inside the central jail in the capital, Dhaka.

A police official who was present during the execution inside the jail confirmed that Qamaruzzman was hanged.

Somoy TV reported that Qamaruzzman was hanged after performing all legal and religious procedures. Channel 24 said Qamaruzzman's body would be taken for burial to his ancestral home in the Sherpur district in central Bangladesh.

Prosecutors say Qamaruzzaman, an assistant secretary general of the Jamaat-e-Islami party, headed a militia group that collaborated with the Pakistani army in central Bangladesh in 1971 and was behind the killings of at least 120 unarmed farmers.

Bangladesh blames Pakistani soldiers and local collaborators for the deaths of three million people during the nine-month war seeking independence from Pakistan. An estimated 200,000 women were raped and about 10 million people were forced to take shelter in refugee camps in neighbouring India.

The execution took place after Qamaruzzaman refused to seek presidential clemency, paving the way for him to become the second person put to death since tribunals were set up more than four years ago to try suspected war criminals.

Authorities heightened security in the capital and elsewhere ahead of the execution.

Members of Qamaruzzaman's family visited him for the last time in Dhaka's central Jail, his lawyer Shishir Manir said.

On Monday, Bangladesh's Supreme Court rejected Qamaruzzaman's final legal appeal against the death sentence given to him by a special tribunal in May 2013. His only recourse would have been to seek a presidential pardon.