The non-governmental organisation (NGO) said 30 countries are now explicitly seeking a ban, after compiling an overview of 97 nations with a stated position on the use and development of what it termed "killer robots".

Most of the 97 want a treaty "to retain human control over the use of force", said New York-based HRW.

"Weapons systems that select and engage targets without meaningful human control are unacceptable and need to be prevented," HRW said in its summary of the overview report, released in Geneva.

"All countries have a duty to protect humanity from this dangerous development by banning fully autonomous weapons. Retaining meaningful human control over the use of force is an ethical imperative, a legal necessity, and a moral obligation."

HRW's "Stopping Killer Robots" overview was prepared in time for a Convention on Certain Conventional Weapons (CCW) meeting scheduled to open in Geneva on Monday.

However, the UN body's gathering has now been put off until much later in the year.

- US, Russia advance -

HRW said the United States and Russia were investing heavily in developing air, land and sea-based autonomous weaponry and were the "most problematic" in blocking a consensus being reached at the CCW.

Though proliferation is not yet widespread, China, Israel, South Korea and certain European nations are also on the move, HRW said.

It said any ban could come through a new CCW protocol, or a treaty via a "standalone process similar to the initiatives that successfully prohibited anti-personnel landmines in 1997 and cluster munitions in 2008".

HRW said a "growing number of countries" sensed a duty to act on stopping fully autonomous weapons.

It said the 30 countries calling for a ban on fully autonomous weapons included Argentina, Brazil, China (use only), Egypt, Iraq, Mexico, Pakistan, the Vatican City and Venezuela.

"Many governments share the same serious concerns over permitting machines to take human life on the battlefield, and their desire for human control provides a sound basis for collective action," said Mary Wareham, HRW's arms division advocacy director and coordinator of the Campaign to Stop Killer Robots, a coalition of more than 160 NGOs.

"While the pandemic has delayed diplomacy, it shows the importance of being prepared and responding with urgency to existential threats to humanity, such as killer robots."

Steve Goose, director of HRW's arms division, told reporters at the United Nations in Geneva that it was not a question of if there would be regulation but when and how comprehensive it would be.

Via video-link, he said there was growing recognition of the dangers such weapons systems posed to international security, not to mention ethics and the law.

However, he warned: "The technology is clearly racing forward whereas some of the diplomatic efforts are stalling" and failing to keep pace.