Microsoft Corp Chief Executive Steve Ballmer said on Thursday the company could look to extend its search engine partnership with Yahoo outside the United States, if it gets regulatory approval.

Earlier this year Microsoft and Yahoo signed a 10-year Web search partnership to challenge Google Inc, a pact that U.S. and European antitrust regulators are evaluating.

It's possible that we will extend that partnership (with Yahoo) outside the U.S., Ballmer told reporters at a news conference. We will have to wait and see if we can get approval and consummate that partnership inside the U.S. first.

Microsoft has said it believes the deal will close in early 2010, and that they can make significant progress on integration in one or two major markets next year.