The NIA has arrested absconding Khalistani terrorist Gurjeet Singh Nijjar at the Delhi airport on his deportation from Cyprus for allegedly hatching a criminal conspiracy to revive Sikh militancy in India for a separate state of Khalistan, an official said on Wednesday.

The premier investigation agency had registered a case in January last year against accused Harpal Singh under the Arms Act, the Maharashtra Police Act and the Unlawful Activities (Prevention) Act.