Robot bricklayers are putting thousands of construction jobs at risk, it has emerged.

The Semi-Automated Mason – or SAM for short – can lay an astounding 3,000 bricks a day in comparison with a construction worker’s average of 500.

SAM’s mortar nozzle pumps concrete onto the brick before its robotic arm places it on the wall.

It is the creation of New York-based Construction Robotics and has already replaced humans on a handful of sites across America.

It’s made up of a conveyor-belt, mortar pump and robotic arm.

One builder helps feed the bricks into the machine, which are picked up by the robotic arm, slathered in mortar, and placed on the wall.

A second worker will smooth over the excess joint mortar.

Construction Robotics is bringing its creation to the United Kingdom “in coming months” and in discussions with construction companies.

‘Robots will soon be on construction sites doing jobs that humans do, but faster.’ - Richard Valentine-Selsey

A third of Britain’s construction workers are aged 50 or older, according to the latest figures.

That means around 620,000 are expected to retire within the next decade — amid a chronic housing shortage.

Richard Valentine-Selsey, a construction consultant, said it was likely that robots would arrive on British building sites within two years.

“Robots will soon be on construction sites doing jobs that humans do, but faster,” Valentine-Selsey told The Times.

The robots have been met with resistance from the construction workforce.

Commenters on the company’s YouTube account, which shows SAM at work, pointed out the robot’s limitations.

One wrote: “Can you post a video of the robot building corners, piers, window openings? Can it adjust coursing or plumbness for screw-ups on the job or wrong steel heights?”

“Can it set lintels and install flashing?”

While YouTube commenters lashed out at the SAM, a company spokesman said that the machine has no problem with piers or window openings and can be adjusted on the fly to handle plumbness. The rep did admit, however, that the machine cannot deal with corners.

SAM costs companies around $20,000 for six units per month and would need heavy supervision.

It’s not just brickies who should beware. A third of jobs are under threat from robots — with transport, factory and retail jobs most at risk, according to accountancy firm PwC.