Two key Bangladesh opposition leaders are set to be hanged within days after losing final appeals to overturn their death sentences, the justice minister said Friday, as authorities completed formalities for their execution.

Two key Bangladesh opposition leaders are set to be hanged within days after losing final appeals to overturn their death sentences, the justice minister said Friday, as authorities completed formalities for their execution.

Bangladesh's Supreme Court on Wednesday dismissed the appeals of Ali Ahsan Mohammad Mujahid and Salahuddin Quader Chowdhury, upholding the death sentence for crimes including genocide committed during the 1971 independence war with Pakistan.

Law and justice minister Anisul Huq said the highest court's orders were read out to the convicts in their cells Thursday night.

He confirmed the two would be executed within days, barring a last-minute presidential reprieve.  

"They were asked whether they would seek mercy to the president. They asked for time to think until this morning," Huq said.

Mujahid, 67, is the second most senior member of Bangladesh's, Jamaat-e-Islami, while Chowdhury, 66, is an ex-lawmaker and a top aide to Khaleda Zia, leader of the main opposition Bangladesh Nationalist Party.

Lawyers said the pair were unlikely to seek mercy because it would require them to admit their war-time guilt.

They are among more than a dozen leaders of the opposition alliance convicted by a controversial war crimes tribunal set up by the secular government in 2010.

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

There are fears the latest verdicts could spark fresh unrest in the nation, which is reeling from a string of killings of secular bloggers as well as the murders of two foreigners in recent months.

Immediately after Wednesday's verdict, authorities shut down Facebook and messaging and voice call services Viber and WhatsApp in an attempt to stop Jamaat supporters from mobilizing to protest against the rulings.

On Friday New York-based Human Rights Watch asked Bangladesh to halt the "imminent executions" of Mujahid and Chowdhury, citing "serious fair trial concerns surrounding their convictions".

"Unfair trials can't provide real justice, especially when the death penalty is imposed," the group's Asia director Brad Adams said.