MANILA (REUTERS) - Pilipinas Shell Petroleum Corp is looking to raise up to 29.7 billion pesos (S$856.01 million) in what could be the Philippines' third and largest initial public offering (IPO) this year.

The unit of Royal Dutch Shell plans to offer 330 million primary and secondary shares at up to 90 pesos per share, a regulatory filing showed on Tuesday.

At the maximum size and price, the IPO would be bigger than the US$532 million maiden share sale on July 18 by Cemex Holdings Philippines, the country's largest issue in three years.

The Pilipinas Shell IPO comes as the benchmark Philippine Stock Exchange (PSE) is showing signs of stability after months of volatility that prompted companies such as Datem Inc and D.M. Wenceslao & Associates Inc to defer their listings.

The PSE soared to a 15-month high last week, with investor confidence getting a boost from expectations that the Philippine economy will continue to outperform some of its Asian neighbours.

"The Philippines is an outlier because economic prospects for our country remains favourable," Noel Reyes, chief investment officer of Security Bank Corp, told Reuters. "We are going to be the safe haven for Asia given that the growth track for other Asian economies is weak."

The IPO is still subject to regulatory approvals and the filing did not provide any timeline but Shell Philippines Chairman Edgar Chua said in March the company was looking to launch it in the second half of 2016.

Pilipinas Shell, which operates one of the country's two oil refineries, is required under a near two-decade old law to offer at least 10 percent of its equity to the public.

It has deferred listing plans several times, citing unfavourable market conditions and the need to upgrade its refinery, which was undertaken last year.

BPI Capital Corp and JP Morgan are handling Pilipinas Shell's IPO.

Pilipinas Shell plans to use the IPO proceeds to fund capital expenditures, working capital and general corporate expenses.