The moratorium was due to expire earlier on Friday but the group had given no indication of its future course of action.
Islam, 26, the chief coordinator of Students Against Discrimination, told AFP from his hospital bed on Monday that he feared for his life.
He said that two days beforehand, a group of people identifying themselves as police detectives blindfolded and handcuffed him, took him to an unknown location.
Islam added that he had come to his senses the following morning on a roadside in Dhaka.
Mahmud earlier told AFP that he had also been detained by police and beaten at the height of last week’s unrest.
Three senior police officers in Dhaka all denied that the trio had been taken from the hospital and into custody on Friday.
THOUSANDS OF ARRESTS
Police told AFP on Thursday that they had arrested at least 4,000 people since the unrest began last week, including 2,500 in Dhaka.
Student protests began this month after the reintroduction in June of a scheme reserving more than half of government jobs for certain candidates.
With around 18 million young people in Bangladesh out of work, according to government figures, the move deeply upset graduates facing an acute jobs crisis.
