A campaign launched last month to pre-emptively ban killer robots was given a boost after a draft UN report called for measure to be taken before their use on the battlefield.
Current military drones and robotic devices cannot decide to fire on targets without human intervention.
But the Campaign To Stop Killer Robots, backed by the New York-based Human Rights Watch, fears that such machines might not be far off.
Above: the UK's prototype Taranis unmanned aircraft
It claims that the drive towards more complex and intelligent drones and other robotic systems could eventually see so-called 'killer' robots employed in modern war.
A new draft report by the UN appears to agree, stating that a moratorium on their use should be put in place.
The draft has been issued by the UN Special Rapporteur on extrajudicial, summary or arbitrary executions for the Office of the High Commissioner for Human Rights, Professor Christof Heyns.
It will be debated in Geneva at the UN Human Rights Council in May.
The draft warns that not only should such robots be banned, but they may already exist in a form if drone supervisors aren't able to properly assess a situation before issuing a command to fire.
It says that such machines "raise far-reaching concerns about the protection of life during war and peace".
The report says "decisions over life and death in armed conflict may require compassion and intuition… Humans - while they are fallible - at least might possess these qualities, whereas robots definitely do not."
"Lethal autonomous robotics, if added to the arsenals of States, would add a new dimension to this distancing, in that targeting decisions could be taken by the robots themselves. In addition to being physically removed from the kinetic action, humans would also become more detached from decisions to kill - and their execution."
However Heyns also notes the arguments of those in favour of an increased role for robots, stating:
Robots "will not be susceptible to some of the human shortcomings that may undermine the protection of life. Typically they would not act out of revenge, panic, anger, spite, prejudice or fear. Moreover, unless specifically programmed to do so, robots would not cause intentional suffering on civilian populations, for example through torture. Robots also do not rape."
The Campaign To Stop Killer Robots has welcomed the draft report, which does not currently constitute the official policy of the UN or its member states.