An RSS office at Payyannur in Kannur was on Tuesday attacked allegedly by CPI-M workers. No one was inside it at the time of the incident, police said.
Only a forensic examination will reveal if the office was set on fire or a petrol bomb was hurled. It has suffered some damage, they said.
BJP workers alleged that the CPI-M was behind the attack. The party called for a strike in Payyanur on Wednesday.
However, CPI-M workers alleged that BJP activists hurled three country bombs at a motorcycle rally taken out by them at Payannur in the evening on the first death anniversary of CPI-M worker Dhanraj who was killed allegedly by RSS activists on July 11 last year.
Four workers suffered minor injuries in the incident, the workers said.
Police said a few houses of workers belonging to both parties were attacked.
Some persons have been taken into custody in connection with the incidents. The situation is under control, they said.