(Adds details on sale, comment from Pemex, paragraphs 3-7)
MEXICO CITY, July 31 (Reuters) - Mexican energy infrastructure firm IEnova, a unit of U.S.-based Sempra Energy , said on Friday it will buy out the 50 percent stake in the pipeline company Gasoductos de Chihuahua owned by Mexican state-run oil company Pemex.
In a statement, IEnova said that the cost of purchase is $1.325 billion and upon completion of the deal, IEnova will be the sole owner of the company.
A finalized deal is expected in 120 days, pending approval by IEnova's shareholders as well as Mexican regulators.
Pemex said in a separate statement that the sale will allow it to "invest in strategic projects that are more profitable, reducing the need to take on debt."
Gasoductos de Chihuahua's assets include three natural gas pipelines, including part of the cross border Los Ramones pipeline in northern Mexico that is the country's most important new link to booming gas supplies in the United States.
Other assets include an ethane pipeline, a liquefied petroleum gas (LPG) pipeline as well as a LPG storage terminal.
Pemex and IEnova will keep a separate joint venture, Ductos y Energeticos del Norte, that is building another phase of the Los Ramones pipeline, both companies said. (Reporting by David Alire Garcia; Editing by David Gregorio)