WASHINGTON -- U.S.President Donald Trump on Tuesday accused Google and other U.S. tech companies of rigging search results about him "so that almost all stories & news is BAD." He offered no evidence of bias, but a top adviser said the White House is "taking a look" at whether Google should face federal regulation.

Google pushed back sharply, saying Trump's claim simply wasn't so: "We never rank search results to manipulate political sentiment."

The president's tweets echoed his familiar attacks on the news media -- and a conservative talking point that California-based tech companies run by CEOs with liberal leanings don't give equal weight to opposing political viewpoints. They also revealed anew his deep-seated frustration he doesn't get the credit he believes he deserves.

The president, who has said he runs on little sleep, jumped onto Twitter before dawn Tuesday to rehash his recent complaints about alleged suppression of conservative voices and positive news about him.

He followed that up with vague threats in Oval Office comments.

"I think Google has really taken advantage of a lot of people, and I think that's a very serious thing. That's a very serious charge," Trump said, adding that Google, Twitter, Facebook and others "better be careful, because you can't do that to people."

Trump claimed that "we have literally thousands and thousands of complaints coming in. ... So I think that Google and Twitter and Facebook, they're really treading on very, very troubled territory and they have to be careful."

Larry Kudlow, the president's top economic adviser, told reporters later that the White House is "taking a look" at whether Google searches should be subject to some government regulation. That would be a noteworthy development since Trump often points proudly to his cutting of government regulations as a spur for economic gains.

In his tweets, Trump said -- without offering evidence -- that "Google search results for 'Trump News' shows only the viewing/reporting of Fake New Media. In other words, they have it RIGGED, for me & others, so that almost all stories & news is BAD. Fake CNN is prominent. Republican/Conservative & Fair Media is shut out. Illegal?" He added, again with no evidence, that "96% of results on "Trump News" are from National Left-Wing Media, very dangerous."

A search query Tuesday morning, several hours after the president tweeted, showed stories from CNN, ABC News, Fox News and the MarketWatch business site, among others. A similar search later in the day for "Trump" had Fox News, the president's favoured cable network, among the top results.

Google, based in Mountain View, California, said its aim is to make sure its search engine users quickly get the most relevant answers.

"Search is not used to set a political agenda and we don't bias our results toward any political ideology," the company said in a statement. "Every year, we issue hundreds of improvements to our algorithms to ensure they surface high-quality content in response to users' queries. We continually work to improve Google Search and we never rank search results to manipulate political sentiment."

Experts suggested that Trump's comments showed a misunderstanding of how search engines work.

Google searches aim to surface the most relevant pages in response to a user's query, even before he or she finishes typing. The answers that appear first are the ones Google's formulas, with some help from human content reviewers, deem to be the most authoritative, informative and relevant. Many factors help decide the initial results, including how much time people spend on a page, how many other pages link to it, how well it's designed and more.

Trump and some supporters have long accused Silicon Valley companies of being biased against them. While some company executives may lean liberal, they have long asserted that their products are without political bias.

Media analyst Ken Doctor said it doesn't make sense for mass-market businesses like Google to lean either way politically. He characterized the complaints as a "sign of our times," adding that, years ago, if the head of General Electric was supporting a Republican candidate, people who disagreed wouldn't then go out and boycott GE products.

"The temperature has risen on this," Doctor said.

Steven Andres, who teaches about management information systems at San Diego State University, said people often assume that if you give a computer the same inputs no matter where you are that you "get the same outputs."

But it doesn't work that way, he said. "You're seeing different things every moment of the day and the algorithms are always trying to change the results."

Trump didn't say what he based his tweets on. But conservative activist Paula Boylard had said in a weekend blog post that she found "blatant prioritization of left-leaning and anti-Trump media outlets" in search results.

Boylard based her judgments on the political leanings of media outlets on a list by Sharyl Attkisson, host of Sinclair Television's "Full Measure" and author of "The Smear: How Shady Political Operatives and Fake News Control What You See, Think, and How You Vote." Sinclair is a significant outlet for conservative views.

Trump began complaining about the issue earlier this month as social media companies moved to ban right-wing "Infowars" conspiracy theorist Alex Jones from their platforms. The president also argues regularly -- and falsely -- that the news media avoid writing positive stories about him and his administration.

Jones is being sued for saying the 2012 shooting massacre at Sandy Hook Elementary School was staged. Jones has since said he believes the shooting did occur and has argued that the lawsuit should be dismissed because he was acting as a journalist.

Trump has praised Jones' "amazing" reputation.

The issue is also of concern on Capitol Hill, where the House Energy and Commerce Committee, chaired by Rep. Greg Walden, R-Ore., recently announced that Twitter CEO Jack Dorsey is scheduled to testify before the panel on Sept. 5 about the platform's algorithms and content monitoring.

Ortutay reported from New York.