(Jared Wickerham/Associated Press)

Google is suing Uber and alleging that a former employee engaged in a “concerted plan” to steal trade secrets related to the search giant's self-driving car technology.

In a blog post Thursday, Google's self-driving car subsidiary, Waymo, said that a former top executive who later went to work for Uber illegally downloaded troves of proprietary data onto an external hard drive before taking the information to his new employer.

“Six weeks before his resignation this former employee, Anthony Levandowski, downloaded over 14,000 highly confidential and proprietary design files for Waymo's various hardware systems, including designs of Waymo's LiDAR and circuit board,” said Google, referring to the laser-imaging system that helps self-driving cars to “see.”

Waymo went on to say that Levandowski pulled down nearly 10 GB of “trade secrets, including blueprints, design files and testing documentation” to an external hard drive before wiping his laptop's hard drive in an effort to cover his tracks.

Although Waymo's blog post singles out only one employee by name, it also references other employees of Uber who were allegedly involved in the plot.

The lawsuit alleges that Uber benefited to the tune of $500 million or more as a result of the alleged theft of intellectual property. Waymo began to suspect Levandowski, it said, when a third-party supplier accidentally copied the Google-owned company on an email that contained diagrams of an Uber circuit board. The circuit board “bears a striking resemblance” to Waymo's own, proprietary technology, according to the lawsuit.

In response, Uber said that it took the allegations “seriously and we will review this matter carefully.”

Levandowski is a major figure within the self-driving car world and was a key member of the team at Google that was working on the technology. That group tested the company's cars as they logged thousands of miles of driving on public roads. In January 2016, Levandowski left Google to help found a company named Otto, which aspires to build self-driving cargo trucks. Otto was bought by Uber last August for nearly $700 million.

At a press event in Pittsburgh last year to debut Uber's autonomous vehicle, Levandowski boasted that the ride-hailing company was finally bringing to fruition a longstanding idea.

“We didn't invent self-driving cars,” he told reporters. “They've been around for a long time. Even in the 1950s there were ads about families playing dominoes” in the cabin of an autonomous car.

The lawsuit comes as the two firms have become increasingly competitive over the future of transportation and automated vehicles. Although Google has worked for years refining its on-road technology, Uber last year debuted its own version of a self-driving car that, under certain conditions, appeared to perform even more smoothly than Google's.

Google was an early investor in Uber, but the companies have grown apart as they have realized the enormous economic potential of vehicles that can ferry people to and fro without a human driver. Both firms believe that fleets of self-driving cars that rove constantly around a city can help reduce traffic congestion, carbon emissions and wasted time.