The US Geological Survey has issued a heightened alert after a volcano on a remote Alaskan island belched a cloud of ash 15,000 feet high, potentially affecting trans-Pacific flight routes.

The eruption burst forth from the Cleveland Volcano on a remote and uninhabited island some 1,500 kilometers (940 miles) southwest of Anchorage.

"Satellite data indicate that this is a single explosion event, however, more sudden explosions producing ash could occur, with plumes exceeding 20,000 feet above sea level," USGS said.

The 5,676-foot (1,730-meter) volcano is currently under an orange alert, the second-highest, denoting either "escalating unrest with increased potential of eruption" or an eruption with "no or minor volcanic-ash emissions."