A Bangladeshi war crimes court has ordered prison authorities to hang Abdul Kader Mullah of the Jamaat-e-Islami party, months after he was sentenced to death.
According to the BBC, Mullah could now be hanged at any time, unless President Abdul Hamid or the Supreme Court intervenes.
The Islamist party has called for a national strike in protest, the report added.
Meanwhile, the human rights groups have said that the war crimes tribunal falls short of international standards.
Mullah was found guilty of crimes against humanity during Bangladesh's independence war in 1971.
He has been accused of being a member of the al-Badr force, which Jamaat is alleged to have created, which is accused of the kidnapping and murder of more than 200 Bengali intellectuals during the war.
A series of killings, including massacres in the Mirpur area of Dhaka, earned him the nickname of "koshai" or butcher of Mirpur.
Mullah was earlier convicted in February and jailed for life.
The sentence was increased by the Supreme Court to the death penalty in September following protests that prompted the parliament to amend a law allowing the state to appeal against any verdict reached by the war crimes tribunal.