Bangladeshi authorities should immediately end the illegal detentions of Hummam Quader Chowdhury and Ahmed Bin Quasem arrested respectively on August 4 and 9, said Amnesty International and Human Rights Watch.

Both were arrested without warrants or charges, have not been produced before a magistrate, and have not been allowed access to family or lawyers,  the New York-based HRW and London-based AI said in a joint statement.

Chowdhury and Quasem are the sons of Salahuddin Qader Chowdhury and Mir Quasem Ali, two senior opposition politicians who were convicted of war crimes during Bangladesh's 1971 War of Independence. Salahuddin was executed in November 2015.

“…Quasem and Chowdhury are subject to an enforced disappearance in the custody of the security forces…,” said Champa Patel, South Asia director at Amnesty International.

Authorities have denied having either of the men in custody, although multiple credible sources have said that both men were at the Rab headquarters in Dhaka on the morning of August 12, according to the statement.

Quasem's wife has filed a general diary and Chowdhury's family attempted to file a GD but the police refused to accept it, it claimed.

“The Bangladeshi authorities have an obligation to pursue those responsible for the heinous crimes…, including of course the horrific attack on the [Gulshan] café,” said Brad Adams, Asia director at HRW.

“But time and time again, we have to call on the government to not give in to its knee-jerk response of arbitrary and secret detentions. The illegal detentions of Chowdhury and Quasem need to end immediately,” he added.