Google has no current plans to launch a search product in China, chief executive Sundar Pichai told US lawmakers on Tuesday as he faced a grilling over privacy concerns and allegations of political bias.

"Right now we have no plans to launch search in China," he said.

There had been reports that Google was set to launch Project Dragonfly as a search engine and re-enter the Chinese market, which the company was largely forced to exit several years back.

The hearing in the Judiciary Committee of the House of Representatives lasted more than three hours and comes amid growing signs lawmakers may seek to impose privacy regulations on big tech companies such as Google and Facebook.

Some of the lawmakers who questioned Pichai tried - and at times failed - to understand how search algorithms work.

Representative Steve Chabot, for example, was upset there were no positive articles on Republican tax cuts on the first page of Google search results - something that could result from the popularity of the tax cut programme or the available online content on the subject, rather than bias.

Some Republicans insisted that individual engineers could influence search results, but Pichai repeatedly rejected the charge, explaining the programming teams are too large and complex.

"I think it is fair to say that most Americans have no idea the sheer volume of information that is collected," committee chairman Bob Goodlatte said. It is nearly impossible to avoid Google, he added.

Pichai said the collection of data was something that users opted into and called it "transparent," while urging customers to review their privacy setting.

Lawmakers were concerned about location data given off by phones, which can be used to track individuals, and how Google stores and handles personal data.

They also noted that Google has changed its privacy policy eight times in the last 24 months, meaning it can be difficult for users to keep up with the current terms and conditions, which are often long texts written in dense legal terminology.

Pichai confirmed that Google cooperates with US government agencies on personal data only when presented with "valid law enforcement requests."

Kevin McCarthy, the Republican majority leader in the House, said the committee must check whether US companies are serving as "instruments of freedom" or of control. The United States needs to know if Google "is on the side of the free internet," he said.