The European Union (EU) has warned Google to modify its proposal to settle antitrust issues over its search practices or will have to face a fine equating to 10% of the its global revenue, or about $6bn.

EU Competition Commissioner Joaquin Almunia has warned that Google’s anti-trust case could be bigger than Microsoft fine which was more than €2.2bn (£1.7bn).

EU Competition Commissioner Joaquin Almunia said: "Microsoft was investigated [by the EC] for 16 years, which is four times as much as the Google investigation has taken, and there are more problems with Google than there were with Microsoft.

"At the beginning of the month I have communicated this to the company asking them to improve these proposals.

"We now need to see if Google can address these issues and allay our concerns."

In February, Google had reached at a settlement with the European regulators and agreed to modify its search practises, ending a three-year EU antitrust investigation and avoiding massive $5bn fine.

However, Google’s proposals were dismissed by Almunia in the wake of heavy criticism and formal complaints from rivals, French and German legislators, lobbying groups, and other commissioners, which made EU to reconsider its original verdict to accept the proposals.

Google has been under scrutiny by the European Commission over claims of misusing its dominant position in online search to its benefit by manipulating search results in favour of its own services and products, such as dedicated search services for hotels and restaurants or shopping, over those of rivals.

Google spokesman Al Verney said: "We continue to work with the European commission to resolve their concerns."

According to EU, if Google’s next antitrust settlement fails, then the next stage would be a fine.

Almunia added: "The next logical step is to issue a statement of objection."