Love your job? Enjoy it while it lasts. There's a 50% chance you're going to be sacked and replaced by a robot.

The Bank of England has warned that machines could take over 80 million American and 15 million British jobs over the next 10 to 20 years. That's roughly 50% of the workforce in each country.

As computers become more sophisticated, they are putting jobs previously thought of as "humans only" at risk of automation, the bank's chief economist Andy Haldane said.

"These machines are different," Haldane said. "Unlike in the past, they have the potential to substitute for human brains as well as hands."

The central bank has highlighted administrative, clerical and production workers as the most at risk of being replaced.

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Haldane said the rise of robots does not necessarily mean skyrocketing unemployment. "Humans will adapt their skills to the tasks where they continue to have a comparative advantage over machines," he said.

This is not the first time that technology has radically transformed the workforce. During the Industrial Revolution, many manual laborers were forced to "skill-up" and move into more sophisticated jobs.

But Haldane warned that this time could be different, because intelligent robots are increasingly taking over mid-skilled jobs, leaving only low-skilled or very high-skilled jobs for humans.

That could squeeze those in the middle, forcing them to "skill-down" and take a job for which they are overqualified.

"The smarter machines become, the greater the likelihood that the space remaining for uniquely-human skills could shrink further," he warned.