The New Zealand Government has labelled killer robots "a threat against humanity".
It comes as the issue of using Lethal Autonomous Weapons (LAWs) was debated by the United Nations in Geneva.
New Zealand was part of a group of 30 countries that called for an outright ban, while others, including superpowers Russia and the USA, resisted rules.
They said the systems needed to be first defined, and the technology could instead help reduce civilian casualties and protect human soldiers.
"There is clearly a majority of countries in the world right now who want to see a new treaty banning and regulating killer robots," said Phil Twyford, Minister for Disarmament and Arms Control.
"There's a small group of highly militarised counties who are blocking that because they want to develop their own weaponry for their own advantage."
He said the problem with the United Nations "consensus-based process" is that it allows one or two countries to block agreement and process even if all other countries are on board.
If that happened, Twyford said, New Zealand would look at other ways to support a new international treaty.
"This is not some dystopian science-fiction scenario, it's almost upon us," he said.
"The prospect of thousands of mass-produced killer robots on the battlefield would be disastrous."
Human rights groups were also strongly advocating for a ban.
"New Zealand might feel quite safe and isolated from the dangers of killer robots but ultimately every country on the planet will be impacted by autonomous weapon systems if that action is not taken now," said Mary Wareham, of Human Rights Watch.
"Killer robots are a new form of warfare."
She said some of this technology was being tested and, in some cases, fielded, including swarms of small autonomous weapons, as well as larger fighter aircraft, ground robots, and tanks.
"The thing they all have in common is that they have no human in cockpit, there is no human on the battlefield with the robot."
The concern was around outsourcing those life-and-death decisions to machines, she said.
"This is the ultimate form of digital dehumanisation... if [LAWs] are allowed to proceed unhindered, we could face a very grim future."