MANILA, Philippines -- A local business family, the Gokongweis, and JP Morgan have expressed interest in buying a 40 percent stake owned by Saudi Aramco in oil refiner Petron Corp., Energy Secretary Angelo Reyes said Wednesday.

Aramco has received an offer of $550 million from London-based investment fund Ashmore Group for the stake, but the Philippine National Oil Co. (PNOC), which also owns a 40 percent stake in the refiner, has first refusal.

Officials said PNOC can also assign its option to a third party. Its board meets Thursday to decide a course of action.

Reyes told reporters: "There are some that expressed interest, the Gokongwei group, and some representatives from JP Morgan."

He said the offers had been referred to PNOC's financial advisers, ING Bank and state-owned Development Bank of the Philippines.

The Gokongweis control conglomerate JG Summit Holdings Inc., which owns the country's second-biggest airline, Cebu Pacific.

It also has interests in property development, food, telecoms and banking, and has a share in JG Summit Petrochemical Corp., a joint venture with Marubeni Corp., which the company says is the first integrated polyethylene and polypropylene plant in the Philippines.

Petron's own petrochemical business is expected to take off this year.

It hopes to increase gasoline production and extraction of propylene, a petrochemical used for food packaging materials and impact-resistant plastics, with the opening of a new facility at its 180,000 barrel per day refinery northwest of Manila.

At current prices, the Ashmore deal values Petron at about P6.22 per share, against the P5.60 it was trading at on Wednesday.

($1 = P42.40)