Security forces in India's north-eastern state of Tripura say some of the tribes people arrested in Bangladesh this week over an arms seizure were connected with separatist rebels in the state.
By Subir Bhaumik
BBC correspondent in Calcutta
They say the rebels may have been using the tribes people to get hold of weapons, ammunition and explosives to boost their armed campaign in the region.
Tripura police chief Mathew John named two of the detainees - Jogesh Debbarman and his son Chittaranjan, from the Bangladesh village of Satcherri - as closely connected with the All Tripura Tiger Force (ATTF).
Mr John said the ATTF's central headquarters were at Satcherri in Bangladesh's north-eastern Sylhet region.
He said the father and son had been helping the ATTF get hold of supplies for the last 12 years, since the rebels set up base in Satcherri.
Scores of Tripura civilians kidnapped by the ATTF had seen the pair mingling with rebel leaders, Mr John said.
The inspector-general of the Border Security Force in Tripura, Alexander Daniels, told the BBC that Jogesh Debbarman was politically influential in the area and had helped the ATTF solve problems with Bangladesh authorities.
Mr Daniels said the number of camps of Tripura rebels in Bangladesh territory had increased and that tribes people were helping them stay in remote hill regions away from Bangladesh security forces.
Bangladesh denies the presence of north-eastern Indian rebels in its territory.
However, Bangladesh police have occasionally arrested some rebels from Assam and Tripura.
Assam separatist leader Anup Chetia is serving a jail sentence imposed after his arrest in Dhaka in 1997.
This week's arrests followed the seizure of a huge amount of ammunition and explosives from a truck carrying pineapples.