The European Parliament has passed a resolution calling for an international ban on so-called killer robots.
It aims to pre-empt the development and use of autonomous weapon systems that can kill without human intervention.
Last month, talks at the UN failed to reach consensus on the issue, with some countries saying the benefits of autonomous weapons should be explored.
And some MEPs were concerned legislation could limit scientific progress of artificial intelligence.
While others said it could become a security issue if some countries allowed such weapons while others did not.
"I know this might look like a debate about some distant future or about science fiction. It's not," said Federica Mogherini, the EU chief of foreign and security policy during the debate at the European Parliament.
"Autonomous weapons systems must be banned internationally," said Bodil Valero, security policy spokeswoman for the EU Parliament's Greens/EFA Group.
"The power to decide over life and death should never be taken out of human hands and given to machines."
The resolution comes ahead of negotiations scheduled at the United Nations in November, where it is hoped an agreement on an international ban can be reached.
In August, experts from a range of countries met at the UN headquarters in Geneva to discuss ways to define and deal with computer-controlled weapons.
"From artificially intelligent drones to automated guns that can choose their own targets, technological advances in weaponry are far outpacing international law," Rasha Abdul Rahim, a researcher on artificial intelligence, at Amnesty International, said at the time.
"It's not too late to change course. 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," he added.
But some countries - including Israel, Russia, South Korea and the US - opposed new measures at the August meeting, saying that they wanted to explore potential "advantages" from autonomous weapons systems.