An official of the health department asking not to be named said the attackers came under the banner of Sarbadaliya Sramik Karmachari Samonnoy Committee (SSKSC) and ravaged union office and the portraits of DCC Mayor Sadeque Hossain Khoka and Prime Minister Khaleda Zia.

Chief Health Officer Colonel Azizul Haq was outside office then.

The SSKSC was formed last month merging five registered organisations including three trade unions and two workers associations of DCC.

Member Secretary of the Samonnoy Committee S M Mosharaf Hossain Milon alleged the activists of Jatiyatabadi Sramik Karmachari Union (JSKU), another faction of JSD, are responsible for the attack.

President of JSKU M Zahangir Alam denied the allegation.

Admitting the incident, Secretary of DCC M Alamgir Hossain told reporters he has informed the mayor of the matter and action will be taken against the persons involved.

Mayor Sadeque Hossain Khoka was not at the office to comment on this incident.

Besides, Mosharaf said some activists loyal to his opponent Zahangir attacked his home on Monday morning and chopped one of his supporters, Jalal, who is now in critical condition in Dhaka Medical College Hospital.

The conflict between the two factions erupted as activists of Zahangir Alam attacked a procession of the Samonnoy Committee in Motijheel and injured at least seven on the way to join the ruling BNP's protest rally in Muktangon on Sunday.

The Samonnoy Committee leaders have filed a case with Motijheel Police Station in this regard.