Members of the Congress have grilled Google's top executive Sundar Pithcai before the House Judiciary Committee, where he was asked, among others, on the reason US President Donald Trump's image appears when a search for the word 'idiot' is carried out.

Republicans on the committee, according to news reports, claimed that the search giant's results are biased.

They accused Democrats who work at the search giant of choosing liberal websites over conservative views for prime placement with regard to the search function.

"Manipulation of search results – I think it's important to talk about how search works," said representative Zoe Lofgren, who allowed Sundar to explain.

"Right now, if you Google the word 'idiot,' under images, a picture of Donald Trump comes up. I just did that.

"How would that happen? How does search work so that that would occur?" she asked.

Sundar then explained how it works.

"We provide search today for – anytime you type in a keyword, we as Google, we have gone out and crawled and stored copies of billions of webpages in our index.

“We take the keyword and match it against webpages and rank them based on over 200 signals, things like relevance, freshness, popularity, how other people are using it. And based on that, at any given time, we try to rank and find the best results for that query.

“Then we evaluate them with external raters to make sure, and they evaluate it to objective guidelines, and that's how we make sure the process is working," he added.

"So it's not some little man sitting behind the curtain figuring out what we're going to show the user. It's basically a compilation of what users are generating, and trying to sort through that information," Lofren said.

Sundar said Google served over three trillion searches last year.

“Just as a fact, every single day, 15 percent of the searches Google sees, we have never seen them before. So this is working at scale. We don't manually intervene on any particular search result," he added.

The Google chief executive officer was also quizzed on competitive dominance, Chinese censorship, and privacy issues.