Bangladesh's prime minister on Wednesday vowed to mete out the "highest punishment to the killers" of a university student who died after he criticised a deal the leader made with India.
The killing of 21-year-old Abrar Fahad on Monday, allegedly by members of a student branch of the country's ruling Awami League party, has sparked two days of protests in Dhaka and other cities.
He was allegedly beaten for six hours in a dormitory not long after posting a Facebook comment criticising Prime Minister Sheikh Hasina for signing a deal allowing India to take water from a river on the border between the two nations.
Some 13 students, including 10 from the Awami League branch, have been detained by police over his death.
"How inhumanly they have beaten him to death. I will never allow it. The criminals will surely face justice," Hasina told reporters as she pledged to inflict the "highest punishment to the killers".
Protesters have called for the attackers to be harshly punished and for the Bangladesh Chhatra League (BCL), the student wing of Hasina's party, to be banned.
"Today it is Fahad Abrar and tomorrow it could be any of us. These dorms have turned into a nightmare for students. We demand an end to torture," Bangladesh University of Engineering and Technology student Fahim Ahmed told AFP.
The prime minister stopped short of acceding to the protesters' other demand that politics be banned on campuses, saying it was up to individual universities.
Fahad had been seen -- in leaked CCTV footage that went viral on social media -- walking into a dormitory with some BCL activists late Monday.
About six hours later, his body was carried out by the students and laid on the ground, the footage showed.
The BCL has earned notoriety in recent years after some of its members were accused of killing, violence and extortion.
Last year its members allegedly used violence to suppress a major anti-government student protest.
The outfit's president and general secretary were sacked last month over allegations they tried to extort money from a state-run university.
The United Nations in Bangladesh said the student died "allegedly for freely expressing his views".
"Campus violence in Bangladesh has over the years affected and claimed too many lives, with apparent impunity for those bearing responsibility," the global body added in a Facebook post.