MANILA, Philippines ? The government on Monday rebuffed an offer to sell its 40-percent stake in local oil refiner Petron Corp. to investment fund Ashmore Group for around $550 million, saying it wanted a higher price.

"We are better off holding to the 40-percent stake," Energy Secretary Angelo Reyes told reporters. "We are not taking advantage of this tender offer."

The London-based fund launched a $827-million tender offer last week for the 60 percent of Petron it does not own. Earlier this year, Ashmore agreed to buy Saudi Aramco's 40-percent stake in the Philippines' largest oil refiner for $550 million.

Last month, a local business family, the Gokongweis, said they had offered to buy the government's stake in Petron for around $579 million or P6.55 a share.

Reyes said no decision had been made on the Gokongwei offer.

"It's slightly higher but we have to be certain that that is the best offer."

Ashmore's tender values Petron at P6.531 a share, the same price it will pay Saudi Aramco and an 11-percent premium to the stock's value the day before the tender, which runs until July 14, was launched.

On Monday, Petron was trading flat at P6.20 a share, up around 2.64 percent.

State-owned Philippine National Oil Co currently holds 40 percent of Petron.

The Philippine government is relying partly on asset sales to prop up its finances after it scrapped its goal of a balanced budget this year and increased spending to support slowing growth.

But Manila wants to hold out for a higher price for Petron, which supplies nearly 40 percent of the county's total fuel needs.