The National Centre for Peace and Conflict Studies says the American drone strike programme to prevent terrorism is ineffective and serves only to fuel Muslim militancy.
On Thursday it emerged a New Zealander, known as Muslim bin John, was killed in Yemen in a drone strike last November. An Australian, Christopher Harvard, 27, also died.
While the New Zealand man is not thought to have been the target of the attack, Prime Minister John Key says it appears the strike was legitimate and he would have been the subject of a New Zealand intelligence warrant.
But deputy director of the National Centre for Peace and Conflict Studies at Otago University, Professor Richard Jackson told Nine to Noon that sort of tacit approval could land New Zealand in trouble.
He said the United Nations and most human rights specialists agree that the drone strike programme does not operate within international law.
Mr Jackson said it amounts to assassinating people without trial or without evidence and if Russia or China assassinated their dissidents in other countries there would be a hue and cry.
Unlikely NZ government had warning
Earlier, an American anti-terrorism expert says it's unlikely the New Zealand Government received advance warning of the deadly drone strike.
Bill Roggio, a senior fellow at the Foundation for Defence of Democracies in Washington DC, told Morning Report Australia would have been notifed as a close ally of the United States.
He said the New Zealander probably was not the target of the attack on a convoy of cars.
Strategic analyst Paul Buchanan said the legality of drone strikes is much debated between those who believe they are legitimate in the war on terror and those who say they are extra-judicial executions without due process.
He questioned if the Government should be comfortable with the killing of a New Zealander on foreign soil who poses no threat to domestic security.
However, Mr Buchanan said the fact is the Australian and New Zealander went to Yemen looking for a fight and they found one.
Family told different version
The grandmother of the Australian man who was killed says her family was told by Australian Federal Police her grandson was killed in a mosque.
New Zealand officials say the pair were killed with three others in a convoy of cars.
Ginette Harvard told Nine to Noon she cannot account for the two different versions but believes Australian officials have repeatedly lied about her grandson's death. She said they have changed their story many times.