Greenpeace wants the government to provide more diplomatic support for the crew of a ship detained in the Russian arctic.
Thirty Greenpeace activists - including the two New Zealanders - are facing piracy charges after a protest against oil drilling.
A spokesperson for Mr McCully says the Ministry of Foreign Affairs and Trade is working closely with other embassies over the Arctic Sunrise detainees.
His office says consular assistance continues to be extended to the New Zealanders, David Haussmann and Jon Beauchamp.
Russian officials claim discovery of narcotic substances on ship
Meanwhile, Russian officials say they have found narcotic substances, including morphine, on board the Greenpeace ship they seized after a protest at an offshore oil rig in the Arctic three weeks ago.
The officials claim they identified raw opium on board Arctic Sunrise, the Greenpeace ship taken under tow to the Russian port of Murmansk.
Greenpeace New Zealand campaign director Carmen Gravatt says that accusation is absurd.
"I've been involved in Greenpeace for 18 years and I've never come across anything and never heard of us being accused of anything like this.
"We have a hospital on board - in that hospital there's a safe. We know that they broke into that safe and perhaps there's something in there that they are referring to."
The Russian investigative committee - Russia's equivalent of the FBI - has hinted the activists could also be held liable for making an attempt on the life and health of the border guards during the seizure of the ship.
Investigators say some of the crew will face charges for other 'serious crimes'.
Greenpeace head suggests 'swap' with activists
Meanwhile, Greenpeace International executive director Kumu Naidoo has written a letter to the Russian president, suggesting himself as security for the release on bail of the 30 activists.
They all remain in custody in Murmansk.