(Reuters) - United Technologies Corp UTX.N is exploring a sale of its Chubb Fire & Security division for more than $3 billion, people familiar with the matter said on Monday.

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On Sept. 14, United Technologies CEO Greg Hayes said the company will announce a decision within 60 days about whether to break up. The company’s main business lines are comprised of aerospace engines, elevators and building equipment such as air conditioners.

Chubb was acquired by United Technologies for about $1 billion in 2003, and is now part of the company's climate, controls and security division. It has been playing catch-up for market share with rivals Securitas AB SECUb.ST and Tyco International Ltd. Tyco was acquired by Johnson Controls International Plc JCI.N two years ago for $16.5 billion.

United Technologies, based in Farmington, Connecticut, has hired Bank of America Corp BAC.N to run an auction for Chubb, the sources said, asking not to be identified because the matter is confidential and cautioning that no deal is certain.

United Technologies did not respond to a request for comment, while Bank of America declined to comment.

United Technologies, maker of Pratt & Whitney engines, Carrier air conditioners and Otis elevators, has a market capitalization of approximately $113 billion. Chubb, headquartered in Britain, provides fire safety and security solutions for businesses and organizations around the world, although its business is predominantly in Europe.

Hayes said at an investor conference this month that United Technologies planned to close its pending $23 billion acquisition of aerospace parts maker Rockwell Collins COL.N by the end of this month. That deal has been held up by China delaying regulatory approval, amid an escalating trade row with the United States.

Investors have increasingly shunned sprawling industrial conglomerates, forcing peers such as General Electric Co GE.N and Honeywell International Inc HON.N to also announce the sale or spinout of major divisions.

Activist investor Bill Ackman’s hedge fund Pershing Square Capital Management LP and Daniel Loeb’s hedge fund Third Point LLC have been putting pressure on United Technologies to break up into three focused, standalone businesses.

(This version of the story corrects year of Chubb acquisition from 2013 to 2003 in third paragraph)