The European Union Competition Commissioner accused Google on 16 April of cheating consumers and competitors by distorting Web search results to favour its own shopping service, after a five-year investigation that could change the rules for business online.

EU Competition Commissioner Margrethe Vestager said the US company, which dominates Internet search engine markets worldwide, had been sent a Statement of Objections - effectively a charge sheet - to which it has 10 weeks to respond.

"The preferential treatment by Google in its general search of one of Google's own products, the shopping comparison service, also known as Google Shopping - what we see is that this favourable treatment over its shopping services constitutes an abuse under EU competition law," Vestager told reporters in a high-profile visit to the United States.

Her findings follow nearly five years of investigation and abortive efforts by her Spanish predecessor, Joaquin Almunia, to strike deals with Google.

"Either for Google to come forward with remedies, which can be turned into binding commitments, or it can go to the direction and end up with a fine for the abuse, if so proven," she warned, if the Commission proves its case that it has used its "near monopoly" in Europe to push Google Shopping ahead of rivals for the past seven years. Google rejected the charges.

Meanwhile, Google's rivals are pushing US antitrust enforcers to investigate the use of Android, two people with knowledge of the matter said.

The Mountain View, California-based company said in a blog post that it strongly disagreed with the EU's statement of objections and would make the case that its products have fostered competition and benefited consumers.

If it finds that companies are abusing a dominant market position, the EU regulator can – as well as charge a fine – demand sweeping changes to their business practices, as it did with US software giant Microsoft in 2004 and chip-maker Intel in 2009.