Bangladesh's Supreme Court on Wednesday upheld death sentences given to two influential opposition leaders who were convicted of war crimes during the country's 1971 independence war against Pakistan.

A special war crimes tribunal convicted Salahuddin Quader Chowdhury of the Bangladesh Nationalist Party and Ali Ahsan Mohammad Mujahid of Jamaat-e-Islami in 2013 of several charges, including genocide and rape during the war.

Attorney General Mahbubey Alam said the court's rejection of the men's appeals cleared the way for them to be hanged unless they seek and get presidential clemency. The men's lawyer, Khandaker Mahbub Hossain, said he would speak to them about seeking clemency.

Shortly after the court's verdict was announced, the Bangladesh Telecommunication Regulatory Authority said in a statement that it had blocked social media sites including Facebook, Viber and WhatsApp for an indefinite period to stop any propaganda that could trigger violence in the country.

Jamaat-e-Islami called for a nationwide general strike Thursday to protest the court's decision.

More than 15 people, mostly leaders of Jamaat-e-Islami, have been convicted of war crimes as part of a series of decisions by two separate tribunals set up by Prime Minister Sheikh Hasina in 2010.