BRUSSELS - U.S. industrial group United Technologies won European Union regulatory approval on Monday to buy the security business of General Electric, boosting its operations in the domestic market.

United Technologies, the world's largest maker of elevators and air-conditioners, expects the $1.82 billion acquisition to reinforce earnings in 2011 and beyond. GE is selling its security arm as part of a portfolio streamlining.

The (European) Commission's market investigation confirmed that the proposed acquisition would be unlikely to raise competition concerns, the European Union executive said in a statement.

Hartford, Connecticut-based United Tech has made a string of acquisitions over the past decade to boost its presence in the security business. Its commercial companies include Carrier air conditioners, Otis elevators and the fire and security arm.

GE Security, part of GE Technology Infrastructure, has about 4,700 employees in 26 countries. Rivals in the security industry include Tyco International, Stanley Works and Japan's Secom Co Ltd.

Hurt by the economic downturn, GE is trimming its diverse stable of businesses.

(Reporting by Foo Yun Chee, editing by Dale Hudson)