The Labour Party is accusing Prime Minister John Key of "ducking for cover" after his belated congratulations to Nobel peace laureate Liu Xiaobo.
The decision to award the Nobel prize to the jailed Chinese dissident has drawn a sharp reaction from the Chinese government.
When asked if he would congratulate Mr Liu on Monday, Mr Key replied he did not want to comment because he had not been briefed on the issue.
Labour leader Phil Goff says anyone who wins the Nobel Peace Prize deserves praise.
And the Green Party says the Government should call for the immediate release of Mr Liu.
Mr Goff says the Nobel prize winner has stood up for democracy and human rights, and the Prime Minister should have spoken up.
"I'm a little disappointed that the Prime Minister has ducked for cover and not made a comment on it.
"We might be a little country, but we've always stood up for our values, and we've never been bullied by anybody or any country, and I hope New Zealand stays that way."
However, Mr Key on Tuesday offered his congratulations to Mr Liu, saying he did not comment on Monday because he has learned it is better to be cautious with diplomatic matters.
Mr Key says Labour acts differently in Opposition than it did in government.
"I find with Labour they're lions in Opposition and lamb chops when they're in government.
"When (former prime minister) Helen Clark was around with the Dalai Lama, she was looking for a used coffee table in some random Koru lounge in a far-flung part of the world.
"When they're in Opposition, they're literally hugging the Dalai Lama, aren't they?"
Foreign Affairs Minister Murray McCully says he has personally raised the issue of human rights with the Chinese government and the case of Mr Liu has been raised by New Zealand officials.