The Philippines' sole oil refinery secured nearly 2.5 million barrels last month after seeing at least four million barrels in shipments cancelled since the start of the US-Israeli war on Iran.

Washington last month eased some sanctions tied to Russia's war on Ukraine to allow countries to purchase Russian oil that was already at sea until April 11 to stabilise energy markets, following the effective closure of the Strait of Hormuz, a key waterway for the world's crude trade.

"We have communicated with the Department of Foreign Affairs for another window or extension of the lifting of the embargo," Philippine Energy Secretary Sharon Garin told reporters, adding the request had been officially relayed to Manila's long time security ally.

While there has been no US response, "we're very positive in getting this other window. If it doesn't come through, we have other options also", she added.

"The Department of Energy sees this current problem as not only a problem for today or next week or next month. It will be a prolonged problem," Garin said.

About 30 percent of the Philippines' crude imports depend on supplies that have to pass through the strait.

The rest of Manila's fuel needs are sourced from Asian refiners that are also dependent on Middle East crude.

The supply crunch has caused local pump prices for key products like diesel to double.

If it fails to obtain more Russian crude, Garin said Manila would look at other sources like Colombia, the United States, and Canada.

While these countries supply different types of crude, "we can still use their refined products", she said, adding Manila would also consider nearer suppliers such as Brunei and India.

"We wanted to open the Russian window but we want more options. We need diversification so that we are not dependent on only one country."

The Philippines has about 50 days' worth of petroleum supply, Garin said.