Prime Minister John Key is still copping criticism for laughing about the escape of convicted killer Phillip Smith - though some New Zealanders are leaping to his defence.

Mr Key was under fire this morning for joking about Smith, who received a life sentence in 1996 for child abuse and murder.

Smith, 40, fled New Zealand last week on a flight from Auckland to Santiago, Chile. He then flew to Rio, via Sao Paulo.

Mr Key cracked a controversial joke when quizzed on whether he would tell Chilean President Michelle Bachelet about Smith's disappearance.

"I'll just let her know there's someone who could be out there from New Zealand that you may not want to invite round for lunch," he told reporters at the APEC summit in Beijing.

Labour leadership hopeful Grant Robertson called Mr Key an "idiot" for making the comment, while his running mate Jacinda Ardern also questioned the Prime Minister's judgment.

Just heard the audio of John Key talking about Phillip Smith's escape....and joking about it. Really Prime Minister? — Jacinda Ardern (@jacindaardern) November 10, 2014

Readers on the ONE News Facebook page are divided on whether Mr Key was in the wrong.

Suzy Jones says his comments were disrespectful to victims of crime and their families.

"I am appalled at our Prime Minister making a joke of this situation that should never have been allowed to happen," she posted.

Alice Hicks says Mr Key's response was "very poor".

"Key needs to take a reality check and get into the real world. The family of the victims must be shuddering."

However, Alexandra Jones says Mr Key was just caught off-guard.

"Lighten up people. Of course he knows the seriousness of it all. It was just light hearted throw away comment in the moment. Like you all haven't done the same thing at some point. Just because he's the PM doesn't mean he has to stop being human."

Grant Tuffery said Mr Key was flippant but that didn't mean he wasn't condemning Smith's crimes.

"Jk stated the facts in a flippant sort of way. At least he wasn't "sorry for being a man". There is absolutely no connection between what JK said and his view on the crimes being committed. We all agree those crimes are disgusting."

Smith, 40, was jailed in 1996 after being confronted by the father of a young boy he had been molesting. Smith stabbed the father to death and was convicted of his murder.

He had been on temporary release from Springhill Prison in Waikato.