Police filed three cases on Monday over arson and vandalism during garment workers' protests in Gazipur, naming around 4,000 people as accused and arresting at least 30.

Gazipur Industrial Police Superintendent Md Amjad Hossain told Daily Waadaa that Gazipur Metropolitan Police had filed one case, while industrial police had filed two others in connection with the incidents.

Police also arrested nine members of the Bangladesh Chhatra League, Jubo League and Swechchhasebak League during raids in different areas on Sunday night.

Speaking to Waadaa, Additional Inspector General of Industrial Police Gazi Jasim Uddin alleged that anti-government political parties are instigating garment workers to create unrest.

Gazi also said several activists of anti-government political parties had been identified through social media.

He said district police, the Special Branch (SB), Detective Branch (DB), Criminal Investigation Department (CID) and other agencies are assisting industrial police in addressing the situation.

Regarding the prime minister's directive to keep all garment factories operational, Gazi said factory owners are responsible for keeping their establishments open and police would take action if anyone attempted to disrupt operations. He also pointed to a shortage of police personnel.

Kaliakoir Police Station Officer-in-Charge Shahidul Islam said workers had blocked the highway in the morning despite the formation of a wage commission board, which he said had raised expectations among workers and reduced the need for protests.

Meanwhile, Gazipur District Administration Executive Magistrate Arif Hossain said 10 platoons of BGB had been deployed in the district to contain the unrest over workers' wage demands.

He said BGB personnel, under the leadership of 21 executive magistrates, took a strong position to maintain law and order.

Earlier in the day, garment workers in Kaliakoir blocked the Dhaka-Tangail highway, staged demonstrations and vandalised vehicles demanding a minimum monthly wage of 30,000 taka.

At least 30 people, including Border Guard Bangladesh (BGB) personnel and journalists, were injured in clashes between workers and law enforcement agencies. 

Several sustained injuries from brickbats and received treatment at local clinics. Traffic on the highway returned to normal around noon after the situation came under control.