The 21 alleged activists of radical outfit Popular Front of India who were taken into custody in connection with seizure of country-made bombs and a sword, are suspected to have terrorist links, police said.
The activists, aged between 20 and 25 years and presently in police custody, have a criminal background and are accused in some cases, including murder, they said.
Two country-made bombs, a sword, raw material for making bombs, some pamphlets in the name of PFI, an identity card of a person who worked in Iran, some foreign currency and a human dummy were recovered by police yesterday during a raid in an under construction building allegedly used as a training centre at Narath in Kannur district.
The activists have been questioned and their mobile call details are being verified, police said.
The Kannur district BJP has demanded a probe by the National Investigation Agency into seizure of the weapons.
Alleging that Kannur has become a centre for "terror" activities, BJP alleged that such centres were functioning at various places in the district.
