Thiel, a Facebook board member, was speaking at the National Conservatism Conference in Washington, D.C. and his speech focused on three questions that should be presented to the tech giant, Axios said.
"Number one, how many foreign intelligence agencies have infiltrated your Manhattan Project for AI (artificial intelligence)?" Thiel reportedly asked. "Number two, does Google's senior management consider itself to have been thoroughly infiltrated by Chinese intelligence?"
He said those questions "need to be asked by the FBI, by the CIA."
Thiel also blasted Alphabet-owned Google for its work in China.
"Number 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," Thiel said, according to Axios.
A Google spokesperson said, "As we have said before, we do not work with the Chinese military."
Last year, Google came under fire after it was revealed that the company was working on a controversial project to launch a censored search service in China.
It was said to be an attempt to get back into the country's web search market following years of absence. Hundreds of employees protested against the project, known as Dragonfly. A report last December said Google had ended its work on the search project.
Another report said Google would not renew a contract with the U.S. Department of Defense that expired earlier this year. The partnership was said to help the Pentagon analyze and interpret drone videos via artificial intelligence.