A police official said dozens of officers, backed by helicopters, forced their way into the mansion, nestled in lush, rolling farmland, after Dotcom refused them entry, a scene more reminiscent of a high-octane spy drama than the usual policeman's lot in rural New Zealand.

"Despite our staff clearly identifying themselves, Mr Dotcom retreated into the house and activated a number of electronic-locking mechanisms," said Detective Inspector Grant Wormald from the Organised and Financial Crime Agency New Zealand.

Officers broke the locks and Dotcom barricaded himself into a safe room which officers had to cut their way through to gain access.

"Once they gained entry into this room, they found Mr Dotcom near a firearm which had the appearance of a shortened shotgun," he said. "It was definitely not as simple as knocking at the front door."