Peter Thiel gave the opening speech at the National Conservatism conference on Sunday.

He used the speech to go after Google for its "seemingly treasonous" relationship with China.

Thiel said the FBI and CIA should investigate Google in a "not excessively gentle manner."

Visit Business Insider's homepage for more stories.

Silicon Valley's most high-profile supporter of Donald Trump has bashed Google for being "seemingly treasonous."

Palantir cofounder and Facebook director Peter Thiel launched an attack on Google during a speech at the National Conservatism conference in Washington on Sunday, Axios and Bloomberg report.

Thiel's criticism centered on Google's relationship with China, alluding to the search giant's attempts to re-enter the Chinese market with a censored search engine, known as Project Dragonfly.

He also raised Google's abandoned contract with the US military to provide AI tools Project Maven, which the company dropped after intense employee backlash.

Read more: Google was grilled about China and other hot-button topics during its investor meeting

According to Axios, Thiel said "three questions" needed to be asked of the company:

"Number one, how many foreign intelligence agencies have infiltrated your Manhattan Project for AI?

"Number two, does Google's senior management consider itself to have been thoroughly infiltrated by Chinese intelligence?

"Three, is it because they consider themselves to be so thoroughly infiltrated that they have engaged in the seemingly treasonous decision to work with the Chinese military and not with the US military... because they are making the sort of bad, short-term rationalistic [decision] that if the technology doesn't go out the front door, it gets stolen out the backdoor anyway?"

The venture capitalist suggested that the FBI and CIA should investigate Google. "I'm not sure quite how to put this, I would like them to be asked in a not excessively gentle manner," he added.

Google was not immediately available for comment when contacted by Business Insider.

The company has acknowledged that work has taken place on a new search engine for China, but the company has repeatedly said that it has no plans to re-enter the country after it left in 2010. "There are no plans for us to consider relaunching our service in China," CEO Sundar Pichai told CNN last month.

Thiel's argument about Google's "treasonous" behavior will play well with Trump's support at a time when the president and many Republicans are animated about the company's perceived anti-conservative agenda. It was only last week, at Trump's Social Media Summit, that the president slammed tech firms for their "terrible bias."