A group of pioneers in artificial intelligence (AI) and robotics have written an open letter to the United Nations urging the organisation to ban any further development of autonomous weapons.

The group of 116 specialists, which include Google's Mustafa Suleyman and Elon Musk of Tesla, have warned of the threat posed by the "third revolution in warfare" posed by weapons using AI.

They sounds the alarm that weapons operating on their own could cause more deaths as they lower the threshold of going into battle.

"Once developed, lethal autonomous weapons will permit armed conflict to be fought at a scale greater than ever, and at timescales faster than humans can comprehend," the letter said.

"These can be weapons of terror, weapons that despots and terrorists use against innocent populations, and weapons hacked to behave in undesirable ways."

The founders have called for lethal autonomous weapons systems to be added to the list of weapons banned under the UN's 1983 convention on certain conventional weapons (CCW).

"We do not have long to act. Once this Pandora's box is opened, it will be hard to close," states the letter, which coincides with the opening of the International Joint Conference on Artificial Intelligence (IJCAI) in Melbourne on Monday (21 August).

Two years ago there was a similar call at the conference by robotics experts to ban the technology. This led to the UN agreeing to further discussions on the ethics of using weapons like drones, tanks and automated machine guns.

Ryan Gariepy, the founder of Clearpath Robotics told the Guardian that autonomous weapons systems "have a very real potential to cause significant harm to innocent people along with global instability."

Professor Stephen Hawking, who is among the letter's signatories, warned in July how human aggression, combined with technology, could hasten the human race's downfall, saying "we need to control this inherited instinct by our logic and reason".

In July 2017, top US general Paul Selva warned against fitting military hardware with autonomous weapons systems, for fear that they could go rogue.