(Adds details of the deals, background)
June 9 (Reuters) - Aubrey McClendon's firm American Energy Partners LLP on Monday said it plans to buy shale oil and gas assets for $4.25 billion, the former Chesapeake Energy Corp CEO's biggest deal package yet in an aggressive bid to build a new company.
McClendon, who co-founded Chesapeake in 1989 and built it into the second largest U.S. producer of natural gas, was pushed out of the company in April last year after he clashed with the board over spending and a governance crisis.
Since then, his Oklahoma City, Oklahoma-based American Energy Partners has secured commitments for $10 billion in financing and its biggest equity investor is Energy & Minerals Group, a Houston based private equity firm run by John Raymond, the son of former Exxon Mobil Corp CEO Lee Raymond.
American Energy, which according to a regulatory filing has about 200 employees including many that worked at Chesapeake, has so far been most active in the Utica shale in Ohio where it plans to drill thousands of wells, it said.
American Energy will enter Texas's Permian Basin by acquiring about 63,000 net acres (25,500 hectares) of production leases from Enduring Resources LLC for $2.5 billion.
The Permian properties are expected to have net production of about 16,000 barrels of oil equivalent per day.
The deals in Ohio and West Virginia, due to close in 60 days, are worth $1.75 billion and include prospective acreage and production.
American Energy will acquire about 27,000 acres of production leases in Monroe County, Ohio, from East Resources Inc and an unnamed private company.
The company is buying 48,000 acres of production leases in West Virginia from East Resources and a private company.
In prior deals, American Energy has agreed to buy acreage from Hess Corp, Exxon Mobil Corp and privately held Paloma Partners this year.
Citigroup and Goldman Sachs were financial advisors to McClendon's firms, while Sullivan & Cromwell LLP, Commercial Law Group, P.C. and Porter Hedges LLP acted as legal advisors. Jefferies LLC was the sellers banker and Baker Botts LLP acted as legal advisor. (Reporting by Anna Driver in Houston and Anannya Pramanick in Bangalore; Editing by Don Sebastian and Marguerita Choy)