BERLIN (AP) -- The European Union's antitrust chief said Tuesday that Google (GOOGL 9.47%) will have to offer more changes to the way it displays search results to settle a pending case.

The period to examine Google's proposals has been extended by one month and his office will ask Google with "almost 100 percent" certainty in June to do yet more, Joaquin Almunia told the European Parliament.

Google's search engine, which is the world's most influential gateway to online information and commerce, enjoys a near-monopoly in Europe with a market share of above 90 percent.

The EU Commission, the 27-nation bloc's antitrust authority, has been investigating since 2010 whether Google is abusing its dominant market position. It pointed out several areas of concern that Google is now trying to address through the proposed concessions.

Google has offered to more clearly label search results stemming from its own services, such as Google News, Google Maps, or its shopping and flight search functions. That would allow users to distinguish between natural search results and others promoted by Google. It also agreed to display some search results from its competitors and links to their services, the EU Commission said last month.

Google said Wednesday it considers its proposals to be sufficient, but pledged again to seek a settlement with the Commission.

"We believe our proposal to the European Commission addresses the four concerns that were raised," said company spokesman Al Verney. "We continue to work with the Commission to settle this case," he added.

Google's concessions were put to a so-called market test, which gives competitors and other interested parties the possibility to provide the Commission with feedback. Once the Commission accepts the remedies, they become legally binding in Europe for Google.

"This market test should have been concluded yesterday, but at the request of some participants we have decided to prolong it by one month," Almunia told lawmakers in Brussels.

"After we have analyzed the responses we have received, we will ask Google probably -- I cannot anticipate this formally -- but almost 100 percent, we will ask Google 'you should improve your proposals,'" the Spaniard said. He didn't specify the areas where Google would need to make improvements.

The complainants against Google include tech giants and Internet companies such as Microsoft (MSFT 2.48%), Nokia (NOK 0.82%), Expedia (EXPE 0.33%), and TripAdvisor (TRIP 1.45%).

The Commission has often taken a harder line with U.S. tech companies than its American counterparts, the Federal Trade Commission and the Justice Department. Google, which is based in Mountain View, California, was able to settle a similar antitrust complaint on its search business with the FTC in January without making any major concessions on how it runs its search engine.

Almunia voiced confidence that the Google case can be resolved by year's end, provided the company accepts the Commission's new requests.

A settlement would remove the threat of a fine against Google and it would not constitute a legal acknowledgment of wrongdoing.

Separately, the Commission is also looking into a complaint that Google allegedly violated competition rules through its Android mobile phone operating system, but has not made a decision yet whether to open a formal investigation, Almunia said.