Prime Minister John Key says people are being radicalised in New Zealand and security services are keeping a watch on them.

The family of an Australian man killed by an American drone strike in Yemen says he encountered radical teaching at a Christchurch mosque, which he didn't like, after earlier converting to Islam.

Photo: RNZ / Patrick Phelps

Christopher Havard was killed in November last year along with New Zealander Daryl Jones, who had dual New Zealand-Australian nationality, and three others alleged to have been members of al-Qaeda. The pair had met in Christchurch and had converted to Islam in their twenties.

Mr Havard's mother Bronwyn Dowrick and stepfather Neill Dowrick have told the ABC that he had converted to Islam in 2008, but became radicalised after he moved to the South Island city.

"They'd gone outside the boundary of what was in (the Koran) and all of a sudden he just up and says, 'How about going to Yemen," Mr Dowrick said.

Photo: RNZ

The mosque says converts go astray because of what they find on the internet and denies it radicalised the man in any way.

John Key won't discuss the mosque or the details of actions by the security services, but said on Wednesday that there is a problem in general.

"There are people in New Zealand who have certainly converted to a form of Islam, and some of those people have gone offshore and got themselves involved in terrorist groups like al-Qaeda. That's a statement of fact."

Mr Key said it is a small number and state agencies are taking steps to monitor them.

A former imam at the mosque said New Zealand authorities would be told if anyone discussed jihad or other extremist Islamic ideas at religious services.

Hisham el Zeiny said alerting authorities is a long-standing policy at the mosque. There are measures in place to pass details of suspicious behaviour on to the president of the Islamic association and he knows who to contact.

He said this policy has not been used so far and the mosque didn't cause Mr Havard's radicalisation.

Mr el Zeiny told Radio New Zealand's Checkpoint programme on Wednesday he was not aware of any radical talk at the mosque, but everyone who attends knows that they are being spied on by the New Zealand and American governments and that may mute any comment.

Internet blamed

The Christchurch mosque in the suburb of Riccarton says converts go astray because of what they find on the internet and they are not taught extremist Islam.

Hisham el Zeiny said he and Mr Havard were staying at the mosque because of recent earthquake damage elsewhere. He said he had no contact with Daryl Jones.

Mr el Zeiny said Mr Havard did not receive any radical teaching there, but converts to Islam typically pick up extreme messages from the internet and there is a limit as to how well this can be checked.

"There is no radical people at the mosque at all," he told Radio New Zealand on Wednesday.

"The problem with those converts, they go to the internet. We don't have a system for them - even if we had a system, the earthquake and everything has been disturbed so most of them go to the internet and that's now they can stray easily.

"We try to monitor as much as we can, but when they go to internet and they don't speak to you about anything you don't know what they are doing. There's nothing apparent in their behaviour, we haven't got a clue. I have my own office in the mosque, so I wouldn't be sitting with them all the time."

Canterbury Muslim Association president Mohamed Jama said Mr Havard seemed just like others who prayed at the mosque five times a day. He said the man worshipped for two years before leaving and making no further contact.

Pair were on Australian watchlist

The ABC, citing documents obtained under Freedom of Information laws, is reporting that Christopher Havard and Daryl Jones had been on an Australian Federal Police watch list because of their links to the banned al-Qaeda in the Arabian Peninsula (AQAP) terror group.

The documents also reveal that Mr Havard was a suspect in the December 2012 al-Qaeda kidnapping of three Westerners in Yemen.

The Australian broadcaster said the documents revealed some confusion within the Australian government about whether the men were involved with AQAP.

In a submission sent to Foreign Minister Julie Bishop's office before the drone strike, they say Mr Jones was only "probably" associated with al-Qaeda, and Mr Havard was only "involved" with the group.

But in another document sent to Ms Bishop a fortnight after their deaths, they refer to the pair simply as "AQAP members".