This is the second international probe agency which has questioned Musa. Earlier, he was quizzed by Bangladesh police in connection with its probe in the July 1 Holey Artisan Bakery attack. 22 people, mostly foreigners, were killed in the attack in July this year.
Official sources said a team of FBI questioned Masiuddin for over five hours during which they focussed their questions around Armar, alias Yosuf Al-Hindi, who is believed to be planning attacks on American assets and nationals world wide.
Armar, 40, a native of Bhatkal in North Karanatka, is suspected to be in touch with radicalised American youth either looking to join or already recruited by the banned ISIS terror group.
The US officials later shared their inputs with the NIA about their questioning of Masiuddin.
The questioning of Masiuddin was allowed on reciprocal basis as the US agency has been extending help to the Indian security agencies in various terror-related cases.
Masiuddin was arrested in July this year during a joint raid by the NIA and West Bengal CID from Viswabharati fast passenger train at Burdwan station in connection with Burdwan bomb blast of October, 2013.
His handler Armar, a fugitive based in Pakistan since 2008, was also part of a group of Indian Mujahideen operatives which had broken away from the organisation to form the IS-affiliated Ansar al-Tauhid in 2014. Ansar al-Tauhid functions from Tehreek-e-Taliban’s training camps in Pakistan's North Waziristan.
Masiuddin spoke about his connections with top leaders of at least two terror groups and admitted that he had been assigned the task of spreading their tentacles in West Bengal and other places in the eastern part of the country.
A resident of Labhpur in Birbhum district, Masiuddin, who was staying in Tamil Nadu's Tiruppur with his family including two children, had visited West Bengal this July after almost six years.
His phone records showed that he had communicated several times with people from Syria, Iraq and Bangladesh. Masiuddin was using a mobile application to keep in touch with top leaders of terror groups in the three countries, NIA sources said.
Masiuddin had allegedly been tasked with beheading his neighbour in Labhpur and raping his daughter to "prove his mettle" over the mobile phone application.
The chat application was similar to one of the main accused of Burdhwan terror case, Suleiman, of the Jamat-ul Mujahideen Bangaldesh and Moulana Yusuf of Ansar-ul-Tauhid, the sources said.