A filed with Auckland's High Court by the Crown Law Office, released on Tuesday by the court, explained the mixup that caused New Zealand prime minister John Key to express "disappointment that unlawful acts had taken place."

Key called for an inquiry on Monday on why the Government Communications Security Bureau (GCSB), which handles signals intelligence, intercepted communications prior to the arrest of Dotcom and his Megaupload colleagues in January.

The Sept. 24 memorandum said the New Zealand's Organised and Financial Crime Agency New Zealand (OFCANZ) sought the assistance of the GCSB in order to conduct simultaneous arrests.

The GCSB is allowed to give that kind of assistance, but only if the people targeted are foreign nationals, the memorandum said. Two of the four people arrested, Dotcom and Bram Van Der Kolk, are permanent residents of New Zealand. The GCSB's spying occurred between Dec. 16 and Jan. 20, the day Dotcom's mansion outside of Auckland was raided.

Finn Batato and Mathias Ortmann, also Megaupload defendants, were named in the memorandum but were not listed as having permanent resident status. Auckland's High Court is scheduled to address the latest surveillance issue on Wednesday.