A "super computer" has duped humans into thinking it was a 13-year-old boy to become the first machine to pass the "iconic" Turing Test, experts have said.
Five machines were tested at the Royal Society in central London to see if they could fool people into thinking they were humans during text-based conversations.
The test was devised in 1950 by computer science pioneer and Second World War codebreaker Alan Turing, who said that if a machine was indistinguishable from a human, then it was "thinking".
No computer had ever previously passed the Turing Test, which requires 30% of human interrogators to be duped during a series of five-minute keyboard conversations, organisers from the University of Reading said.
But "Eugene Goostman", a computer programme developed to simulate a 13-year-old boy, managed to convince 33% of the judges that it was human, the university said.
Professor Kevin Warwick, from the University of Reading, said: "In the field of artificial intelligence there is no more iconic and controversial milestone than the Turing Test.
"It is fitting that such an important landmark has been reached at the Royal Society in London, the home of British science and the scene of many great advances in human understanding over the centuries. This milestone will go down in history as one of the most exciting."
The successful machine was created by Russian-born Vladimir Veselov, who lives in the United States, and Ukrainian Eugene Demchenko who lives in Russia.
Mr Veselov said: "It's a remarkable achievement for us and we hope it boosts interest in artificial intelligence and chatbots."
Prof Warwick said there had been previous claims that the test was passed in similar competitions around the world.
"A true Turing Test does not set the questions or topics prior to the conversations," he said.
"We are therefore proud to declare that Alan Turing's test was passed for the first time."
Prof Warwick said having a computer with such artificial intelligence had "implications for society" and would serve as a "wake-up call to cybercrime".
The event on Saturday was poignant as it took place on the 60th anniversary of the death of Mr Turing, who laid the foundations of modern computing.
During the Second World War, his critical work at Britain's code-breaking centre at Bletchley Park helped shorten the conflict and save many thousands of lives.
Instead of being hailed a hero, Mr Turing was persecuted for his homosexuality. After his conviction in 1952 for gross indecency with a 19-year-old Manchester man, he was chemically castrated.
Two years later, he died from cyanide poisoning in an apparent suicide, though there have been suggestions that his death was an accident.
Last December, after a long campaign, Mr Turing was given a posthumous Royal Pardon.