"Bombs were recovered from the tomb by a BJP worker at Muzhappilangad beach near Kannur," police said.
Police suspected that the bombs were kept there to ward off political rivals from vandalising the tomb.
Acting on a tip off, a police team searched the tomb Sooraj, who was killed in 2005 allegedly by CPI-M workers, and found three steel bombs on Thursday.
The bombs were defused. According to police sources, there was a strong ground to believe that the placing of the bomb in the tomb was a strategy to pre-empt destruction of memorials by political rivals of the victims.
This particular tomb itself was destroyed earlier and was rebuilt by BJP workers.
Scores of BJP-RSS and CPI-M workers have been killed in political violence in sensitive pockets of Kannur district over the last three decades.
However, in the last few years, there has been a lull in clashes with both sides exercising restraint.