India's anti-terrorism agency has "credible information" that the six stage an operation targeting a civilian passenger plane

Six Ukrainians and an American described as "mercenaries" and currently being held in prison launched a drone attack on a civilian aircraft in neighboring Myanmar, India's anti-terrorism agency told a Delhi court.

The seven were arrested by the National Investigation Agency (NIA) in March while trying to depart India from different parts of the country.

A first-person view drone (FPV) of the type that is widely used in the Ukrainian conflict struck a Myanmar National Airlines ATR-72-600 while preparing to depart from Myitkyina Airport to Mandalay, on February 20, Burmese media reported at the time. 

The passenger-laden plane suffered damage to its nose, mid-fuselage, and tail sections. It is not clear if the NIA was referring to the same attack.

The agency previously told the court on August 19 that the Indian government "has received credible information indicating the involvement of certain Ukrainian and US nationals in a drone attack on a civilian aircraft in Myanmar." 

The court granted the agency permission to interrogate two from the group - Ukrainian Viktor Kaminskyi and American Matthew VanDyke - in prison.

The details of the court filings were reported by the Indian Express on Friday.

The NIA said in total 14 Ukrainians entered India on tourist visas on different dates and flew to Guwahati in the northeastern state of Assam, where they traveled to the state of Mizoram without the required permits, and entered Myanmar illegally to conduct a "pre-scheduled training on drone warfare, drone operations, assembly, and jamming technology" for ethnic armed groups fighting the military government.

The NIA said many of the ethnic armed groups in Myanmar are also known to support certain banned Indian insurgent groups with weapons, military hardware, and training.

Several consignments of drones from Europe were delivered by the accused to individuals and groups in Mizoram,according to the NIA. The arrested mercenaries also allegedly confessed to have been in contact with and helped "unknown terrorists carrying AK47 rifles."

The agency said it wants to confront Kaminskyi and VanDyke with certain witness statements to "unearth the larger conspiracy" in the case, details of the other suspects, and the masterminds of the operation.

It said data extracted from seized devices contained images, videos, voice samples, among other things, which have to be corroborated with direct questioning.

Kiev has "any insinuations regarding the possible involvement of the Ukrainian State in supporting terrorist activities" and demanded that India release its nationals.

VanDyke, the American, is the founder of Sons of Liberty International, which provides military training in conflict zones. He has reportedly been involved in other conflicts, including fighting with Libyan rebels in 2011.

The court in July allowed him special food items and a cook after he complained that the "spicy and oily" prison meals affected his health, but it rejected his request for treatment at a private hospital, and to communicate with his family in the US.