Police have identified the deceased as Babul Sardar, 48, organisational secretary of metropolitan unit (south) of the BNP's workers' front and chief of the Sramik Dal Dhanmondi unit.
Office Secretary of the Sramik Dal metropolitan unit Abu Kausar Bhuiyan, 45, was also injured in the clashes that broke out on Sunday afternoon.
Sramik Dal activists took both to the Dhaka Medical College Hospital with injuries, the hospital police outpost Inspector Mozammel Haque told bdnews24.com.
"They had said that Chhatra Dal activists had attacked them."
Sardar was in critical condition, Haque said quoting doctors.
He was later taken to City Hospital in Lalmatia, where he died while undergoing treatment, DMP's Motijheel division Deputy Commissioner Anwar Hossain said.
He said the Sramik Dal's 'Sardar Group' and 'Shahid Group' were embroiled in the clash. Some activists of Chhatra Dal, the BNP's student wing, sided with the Shahid Group and joined the fight.
The clash began after a special prayer was held for ailing senior BNP leader Sadeque Hossain Khoka's recovery.
Some BNP activists said Sardar and Bhuiyan were attacked following a dispute over the formation of the Sramik Dal's Dhanmondi unit committee.
Source: Bangladesh's First Internet Newspaper