New Delhi: The NIA on Tuesday filed a chargesheet against seven foreign nationals, including US citizen Matthew Aaron Van Dyke, for illegal entry, stay and movement, but did not invoke the anti-terror law UAPA, after arresting them in a terror conspiracy case for alleged links to ethnic armed groups in India.The National Investigation Agency NIA chargesheet, filed before Special Judge Prashant Sharma, accused the seven of offences under sections 21 and 23 of the Immigration and Foreigners Act.The NIA had arrested Van Dyke on March 13, along with six Ukrainian nationals - Kaminskyi Viktor, Hurba Petro, Slyviak Taras, Ivan Sukmanovskyi, Stefankiv Marian, and Honcharuk Maksim - after they allegedly infiltrated India from Myanmar through the Mizoram border before being intercepted at various domestic airports across the country.Also read: Fake government ID, gun: 2 held after forced entry at Mumbai's Jio World Plaza; no connection to PM Modi's event, say PoliceIt was alleged that the group was operating as mercenaries.The NIA had earlier registered a case against them under Unlawful Activities (Prevention) Act provisions along with sections of the Bharatiya Nyaya Sanhita (BNS).However, it did not invoke the stringent UAPA against them in the charge sheet.The agency had earlier told the court that the accused were being probed for a wide-ranging terror conspiracy, including assistance to ethnic armed groups in India and Myanmar, and imparting drone training to them.Also read: Satya Niketan building collapse: Supreme Court to hear case on September 10; may transfer matter from High CourtOn March 16, the court allowed the NIA 11 days' custody of the accused. They were later remanded in judicial custody.