At least 19 people including six policemen were injured in separate clashes between police and activists of Jamaat-e-Islami and Islami Chhatra Shibir in Chapainawabganj and the capital.
Police detained 25 Jamaat and Shibir men in Uttara and arrested 16 in Chapainawabganj. In another drive at the capital's Malibagh, they detained six activists.
The clash at Uttara erupted around 4:30pm when police intercepted a procession of 60-70 members on Road 7, Sector 4, witnesses said.
They hurled brick chips at police when the latter marched forward to stop them. Police and the activists chased each other for about 10 minutes.
Police fired eight rounds of teargas canisters, 18 rounds of rubber bullets and baton-charged the supporters to disperse them, Deputy Commissioner Nisarul Arif of Dhaka Metropolitan Police (Uttara division) told The Daily Star.
Police arranged primary treatment for three activists. No policemen were injured in the incident.
The procession was part of Jamaat and Shibir's ongoing demonstrations demanding release of their leaders facing trial for crimes against humanity committed during the Liberation War of 1971, police said.
In Chapainawabganj, 16 people including six policemen sustained injuries during a clash between police and Jamaat-Shibir men at Nachole Bazar yesterday.
The injured police personnel are: Officer-in-Charge Firoz Ahmed, Officer-in-Charge (Investigation) Sayed Iqbal, Sub-Inspectors Abdul Momin and Saiful Islam and Constables Mamunur Rashid and Helal of Nachole police station.
Firoz was admitted to Nachole upazila health complex and the others were given first aid. Police arrested five leaders, including upazila unit ameer Yahia Khaled, secretary Yakub Ali and Nachole union parishad Chairman Mawlana Rais Uddin.
Police said the activists brought out a procession without the local administration's permission around 3:45pm and attacked them with brickbats and sticks. Police retaliated with teargas shells, rubber bullets and baton charge.
In the Malibagh drive, six Jamaat and Shibir supporters were picked up from Educare Coaching Center around 5:00pm, following a tip-off, said Officer-in-Charge Mohammad Shah Alam of Ramna Police Station.
Since November 5, Jamaat and Shibir members have repeatedly attacked police across the country and left many of them injured.