Siliguri, May 23 :    Siliguri, May 23:  The arrest of three top Bodo militant leaders from a Siliguri hotel has again raised speculations that the region is being used as a transit point by Northeast rebels operating from Nepal. National Socialist Council of Nagaland (Isak-Muivah) leaders Isak Chishi Swu and Thuingaleng Muivah had been regularly visiting Kathmandu since 1992, intelligence sources said. The Naga group, they said, had been sending its recruits for training at an institute near Lalitpur. 'The NSCN(I-M) also has a close nexus with local political outfits, especially ultra-Left ones like the Communist Party of Nepal (Maoists).' They claimed David Ward, a Britisher, has 'volunteered' to work for an organisation called Naga Vigil and visits Kathmandu regularly to raise funds. 'Ward is known for his liaisoning with Pakistani officials in Islamabad and in eastern and Northeastern India,' an intelligence official said. According to a recent army intelligence account, a group of 17 Naga insurgents crossed over to Nepal from India at Panitanki-Kakarbhitta border near Siliguri last year. 'The group, on reaching Kathmandu with Bangladeshi passports, reportedly checked into a popular hotel and then headed towards China.' The army believes the on-going anti-national activities in southern Bhutan have forced many Bhutanese to flee and take shelter in a camp in eastern Nepal. 'This has provided a golden opportunity to United Liberation Front of Asom (Ulfa) and other Northeast groups to mingle with the Bhutanese and take shelter in refugee camps,' said a Siliguri-based army intelligence official. Last month, the Bhutan Army deployed more than 3,000 soldiers along the kingdom's southern border with Assam. 'Ten new camps have been set up along the 250-km border to neutralise the intrusion of rebel groups from Assam into southern Bhutan,' a Bhutan Army source said. The Indian Army, too, has set up several camps along the Bengal-Assam-Bhutan border tri-junction near Sankosh tea estate. 'Taking advantage of the situation on the eastern border of Nepal - some places along the border are under the control of Maoist rebels - Ulfa has set up its transit camps at Illam, Jhapa, Tapelgunj and Panchtar in Nepal. Ulfa and National Democratic Front of Bodoland (NDFB) rebels have also been procuring arms and ammunition from this Nepal corridor,' an intelligence official said. Army sources claim most insurgent groups have the backing of Pakistani mercenaries in Kathmandu. They say seizure of a huge quantity of explosives from Pakistani diplomat Mohammad Arshad Cheema's residence at Kathmandu earlier this year is just the 'tip of the iceberg' of Islamabad's espionage, subversion and psychological warfare against India mounted from Nepalese soil. 'In the eighties, the ISI started making moves and President Zia-ul-Haq launched his long-term anti-India scheme - Operation Topac. Given the acute poverty in the Himalayan kingdom, theISI did not find it difficult to get a secure foothold in the place once it opened its purse wide,' sources said.