Police in the US have been quietly testing a highly-advanced robot dog alongside officers, prompting an urgent response from a civil liberties group

The American Civil Liberties Union made a public records request to robotics firm Boston Dynamics after the Massachusetts State Police published a video demonstration of the Spot robot dog.

It is believed the robotic dogs, which are capable of opening doors and navigating obstacles, have already been used during live incidents.

"All too often, the deployment of these technologies happens faster than our social, political, or legal systems react," the ACLU said in a statement shared with TechCrunch.

"We urgently need more transparency from government agencies, who should be upfront with the public about their plans to test and deploy new technologies."

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A spokesperson for the Massachusetts State Police said the robot was being used as a "mobile remote observation device" to monitor suspicious activity.

“Right now, our primary interest is sending the robot into situations where you want to collect information in an environment where it's too dangerous to send a person, but not actually physically interacting with the space,” the spokesperson said.

The lease agreement between Boston Dynamics and the police reportedly includes the condition that it is not used to "physically harm or intimidate people".

(Boston Dynamics (Boston Dynamics)

Boston Dynamics announced earlier this year that it would begin selling the canine-inspired machines at some point in 2019, though no date or price was provided.

The product page for the Spot describes it as a "nimble robot" capable of operating autonomously and travelling for up to 90 minutes at a time.

Promotional materials for the Spot robots show them being used in a variety of roles and environments, ranging from assistants at construction sites, to remote security guards.

"There's a remarkable number of construction companies we're talking to," Boston Dynamics chief executive Marc Raibert said at the time.

"But we have some other applications that are very promising, [such as] in hostile environments where the cost of having people there is high."

The robots have frequently been described as "creepy" and "terrifying", though Mr Raibert claimed that they have been misrepresented. In a recent demonstration of the technology, he said it "really bothers me" when they are referred to in this way.