Joey Campos, manager for strategic planning of Petron Corp , said the firm needed to invest about 4.5 billion pesos to meet cleaner petroleum standards by 2004.

Under the "Clean Air Act" law signed by President Joseph Estrada last June, the country's three oil refiners were required to phase out lead in gasoline only by January 2001.

It should also contain no more than 45 percent aromatics and not more than four percent benzene within six months.

The law also stipulated that by 2003 all gasoline sold in the Philippines must contain no more than 35 percent aromatics and two percent benzene. Lower aromatics and benzene mean reduced airborne pollution.

Energy Secretary Mario Tiaoqui told reporters early this week the government wanted to advance the implementation of the ban on lead in gasoline in the capital Manila by January 2000.

"By December, we could...phase out already low-lead gasoline in Metro Manila," Campos told Reuters in a telephone interview.

Officials of Pilipinas Shell Petroleum Corp and Caltex (Philippines) Inc also said they were ready to shift to the production of unleaded gasoline before January 2000.

Pilipinas Shell is a unit of the Royal/Dutch Shell group , while Caltex is a unit of the joint venture between Chevron Corp and Texaco Inc .

Campos said gasoline currently produced in the country have an aromatics content near 45 percent and benzene not far from four percent.

Unleaded gasoline is cheaper by 34 centavos per litre compared with leaded gasoline because of lower taxes. The government imposes a tax of 4.35 pesos per litre of unleaded gasoline and 5.35 pesos on leaded gasoline.

The Philippines consumes around 370,000 barrels of petroleum products a day, of which 20 percent is gasoline, an industry analyst who declined to be identified said.

The analyst said metropolitan Manila accounted for about 60 percent of the total gasoline demand per day. Seventy percent of the gasoline sold in the country is leaded, the same analyst said.