New Delhi: The National Investigation Agency (NIA) on Thursday "formally arrested" Tahawwur Hussain Rana, the key accused in the deadly 26/11 Mumbai terror attacks, immediately after he landed at the Delhi airport following his extradition from the United States, according to an official statement.

Rana was escorted to Delhi by teams of NIA and National Security Guard, comprising senior officials, on a special plane from Los Angeles, the statement said.

The NIA investigation team at the airport arrested Rana, a Canadian national of Pakistani origin living primarily in Chicago, soon after he emerged from the airplane, after completing all the necessary legal formalities, it said.