Experts from across the globe are meeting to discuss ways to define and deal with "killer robots" — futuristic weapons systems that could conduct war without human intervention.

The weeklong gathering is the second this year at U.N. offices in Geneva to focus on such lethal autonomous weapons systems and explore ways of possibly regulating them, among other issues.

Some top advocacy groups say governments and militaries should be prevented from developing such systems, which have sparked fears and led some critics to envisage harrowing scenarios about their use.

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As the meeting opened Monday, Amnesty International urged countries to work toward a ban.

Amnesty researcher on Artificial Intelligence Rasha Abdul Rahim said killer robots are "no longer the stuff of science fiction," warning that technological advances are outpacing international law.

"It's not too late to change course," Rahim said in a statement. "A ban on fully autonomous weapons systems could prevent some truly dystopian scenarios, like a new high-tech arms race between world superpowers which would cause autonomous weapons to proliferate widely."