Google has denied it promotes its own websites and services over others.

Executive chairman Eric Schmidt told a US Senate hearing: "May I simply say that I can assure you we're not cooking anything."

The Senate Judiciary subcommittee on anti-trust is currently seeking to establish whether the search engine is abusing its position in the market and subsequently hampering competition.

"Google does nothing to block access to any of the competitors and other sources of information," Schmidt said.

"Google is focused on delivering the best search results, not driving business to its services."

Consumer review site Yelp and comparison shopping site Nextag told the hearing Google's search practices were hurting their businesses. However, Schmidt denied this was true.

"Most of these complaints come from websites that don't like where their sites rank on Google's search results page or argue that in providing better answers like maps, shopping, or local results, we are hurting individual sites," Schmidt said.

"If consumers don't like what one website is providing them, they can switch to another website with just one click."

The Senate hearing comes three months after the US Federal Trades Commission (TFTC) launched an investigation into whether Google's search results steer web users to the firms service rather that those from rival companies.

Furthermore, the European Commission launched an investigation into the search engine last year after three complainants accused it of demoting rival sites in search results and giving preference to its own services. British price comparison site Foundem and French legal search engine are behind complaints to the commission about "unfavourable treatment of their services in Google's unpaid and sponsored search results coupled with an alleged preferential placement of Google's own services".