A key test of their unity would be on Sunday, at a protest rally in Delhi to which AAP has invited all opposition parties
Sources in West Bengal police said a Special Operation Group (SOG) of the CID detained them on Friday afternoon and seized some incriminating documents from them.
Eight of the arrestees were male and seven female, police said adding four children were also with them.
They reportedly entered India through Benapole border and were planning to go to Mumbai.
Police, however, refused to divulge further details saying it would “hamper their investigation process”.
Police are trying to find out whether the arrestees have any terror link.