Google shares were marginally down Wednesday morning on the Nasdaq.

London - Google has been ordered by competition regulators to end “abuses” of its market dominance or risk being fined billions of pounds.

The search engine, which has more than 80 percent of the global market share, is accused of promoting its own products and effectively locking out rival advertisers.

The European Commission has written to the US giant highlighting four areas where “Google business practices may be considered as abuses of dominance”.

It has set a deadline of a “matter of weeks” for the company to propose solutions.

If these are not satisfactory, the EC will begin a formal investigation, which could lead to it imposing huge fines and its own measures.

The announcement heralds the most significant transatlantic anti-competition row since Brussels went to war with Microsoft a decade ago.

It will also embarrass the Tory Party which has forged close links with Google, as revealed by the Daily Mail last week.

Research revealed that ministers, including David Cameron, had met executives an average of once a month since the election.

Joaquín Almunia, the EU’s competition chief, has written to Google executive chairman Eric Schmidt demanding action.

He said Google favours its own products in search results and “copies” content from rivals without permission.

It also stifles competitors with advertising deals with other websites and restricts them from moving their online campaigns to rival search engines, he added.

The review of Google’s business practices started in 2010 after complaints from rivals.

The commission can levy fines of up to 10 percent of revenue, which could amount to billions of pounds.

Google has agreed to look into the EC’s concerns, though it disputed its conclusions. A spokesman said competition on the web has increased “dramatically” and the company faces “tremendous” pressures.

The US Federal Trade Commission has launched a similar investigation into claims of anti-competitive practices by Google. - Daily Mail