(Reuters) - Private equity firm Blackstone Group LP and LLOG Exploration Company LLC will jointly invest $1.2 billion to strengthen the offshore oil producer's operations in Mexico, the two firms said on Tuesday.

Blackstone will invest from its two private equity funds, which aggregate over $19.3 billion of committed capital, including Blackstone Energy Partners.

The partnership will boost LLOG's asset base in the Gulf of Mexico and appraisal of about 110 offshore leases.

"LLOG is a highly efficient deepwater operator, with the history and ability to accelerate development, minimizing the timeframe to first production and significantly increasing project returns," said Angelo Acconcia, managing director of Blackstone Energy Partners.

(This story was fixed to clarify both Blackstone and LLOG Exploration will invest in JV)

(Reporting by Neha Dimri in Bangalore; Editing by Mark Potter)