New Zealand Prime Minister John Key wants Japan to apologise for breaching the country's exclusive economic zone (EEZ). The Shonan Maru No 2 entered New Zealand's EEZ while tailing one of the ships of anti-whaling organisation, Sea Shepherd.

Although entering 200 nautical miles in New Zealand's EEZ is not illegal, Kiwi officials have previously warned the Japanese government that any action to cross the EEZ will be treated as an unwelcome and offensive gesture.

On Feb 10 in Wellington, the Japanese ambassador was summoned over the matter, but the New Zealand prime minister wanted Japan to issue a formal apology. According to reports, Mr Key said an official apology will be "good."

New Zealand Foreign Affairs Minister Murray McCully said the Japanese whaling ship did not enter the country's territorial which extended 12 nautical miles from the coast.

Mr McCully said he was advised that the Japanese whaling ship Shonan Maru 2 was following the anti-whaling ship Sea Shepherd in New Zealand's EEZ. He gave instructions to the Kiwi embassy officials in Tokyo to send a message to Japan that breaching the EEZ will not be welcomed.

The Foreign Affairs Minister has vowed to take more steps to ensure that the Japanese government knows how its whaling ship has caused deep offence to the country.

Meanwhile, a spokesman for the Japanese government said their ships did not cause problems from the perspective of international law. Japan's chief cabinet secretary Yoshihide Suga said the Japanese whaling vessel was "taking protective moves" and "intruding" on New Zealand's EEZ was part of the plan.

According to the Japanese government, whaling has long been a cultural practice. The country allows whale hunts under its "scientific research provision" in the moratorium on whaling.

New Zealand's Green Party had called on the government to protest the breach instead of just condemning it. According to reports, Greens spokesperson Gareth Hughes said New Zealand should file a formal complaint or a diplomatic protest in Tokyo.