The sons of two Bangladesh opposition politicians convicted of war crimes during the country's 1971 war of independence have been detained by authorities, relatives of the two men told Al Jazeera.

Relatives said that Hummam Quader Chowdhury, 33, the son of the late Salauddin Quader Chowdhury, a leader of the Bangladesh Nationalist Party who was executed in 2015, was arrested last week.

Mir Ahmed Bin Quasem, 32, the son of Mir Quasem Ali, leader of the Jamaat-e-Islami party whose appeal against execution for war crimes has been rejected, was held on Tuesday.

A senior Bangladesh police official denied any knowledge of the detentions.

Hummam Quader Chowdhury’s mother, Farhat, said that her son was picked up by men in civilian clothes on the morning of August 4 as they were travelling by car to attend a court hearing in Dhaka.

"Some men in plain-clothes opened the right hand back door where Hummam was sitting, and asked: 'Are you Hummam Quader Chowdhury?' My son said: 'Yes'. They told him to get out," Farhat said.

"I said he could not go as he had to go to court. But the men said with great authority: 'No, he is coming with us'."

Some among the group of eight to 10 men who took Hummam were armed and claimed to be police detectives, said Samshad Sayem, who was sitting in the front seat of the car.

Sayem said he tried to follow the group on foot but they threatened violence if he persisted.

Mir Ahmed, the son of imprisoned Jamaat-e-Islami party leader Mir Quasem Ali, was taken from his home in the Mirpur area of Dhaka on Tuesday night, his sister Tahera Tasnim said.

The men who took her brother, who is a lawyer, wore civilian clothes, did not show an arrest warrant and did not identify themselves as members of a law enforcement unit.

"They did not wear any uniform and they had no legal arrest warrant," she said.

"Nothing. They just said, 'Come with us'. They did not give any reason why they wanted to take him. They did not say why they were taking him or where they were taking him."

Bangladesh's Deputy Inspector General of National Police AKM Shahidur Rahman said he knew nothing about the two men.

"I know nothing about this," he said.

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The disappearance of the two men follows just weeks after local newspapers reported that Prime Minister Shiekh Hasina said she believed plans were being hatched to free Mir Quasem Ali from prison.

Home Minister Asaduzzaman Khan Kamal also told reporters that "setting Mir Quasem free" was one of the motives behind recent attacks in Bangladesh, including the hostage takings and killings at the Holey Artisan Bakery in Dhaka on July 1, in which killed 22 people. 

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Although the Holey Bakery attack was claimed by the Islamic State of Iraq and the Levant (or ISIL, also known as ISIS), the Awami League government has been reluctant to acknowledge links between local attacks and ISIL, and regularly blames opposition parties for the violence.

According to the local human rights organisation, Ain o-Salish Kendra, the disappearance of Hummam and Mir Ahmed coincides with an increase in alleged detentions and extra-judicial killings by Bangladesh law enforcement in response to attacks in recent months.

Two men, who were present at the Holey Artisan Bakery when it was attacked, were secretly detained by authorities for 30 days before they were brought to the court last week to be charged in connection with the attack, according to their families

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Source: Al Jazeera