A volcano on an uninhabited island erupted early Wednesday, spewing ash about five miles into the sky and prompting air traffic authorities to warn planes to steer clear of the cloud.

The ash from Augustine Volcano was not expected to reach Anchorage, the state's most populous city nearly 200 miles to the northeast, meteorologists said.

Flights were restricted temporarily in a five-mile radius around the volcano and for 50,000 feet above it, said Federal Aviation Administration spokesman Mike Fergus. The ash can clog jet engines.

Cargo or passenger traffic from Asia usually fly through the area to Anchorage but could be easily rerouted, Fergus said. "It's not posing any significant traffic problems," he said.

The cloud, moving at about 20 mph, appeared to have low concentrations of ash, said Bob Hopkins of the National Weather Service office in Anchorage.

Residents on the Kenai Peninsula, east of the volcanic island, reported seeing ash, said geologist Jennifer Adleman of the Alaska Volcano Observatory.

The few residents in the area were warned to reduce outdoor activity, keep windows and doors closed, and avoid outdoor exercise.

The 4,134-foot volcano last erupted in 1986. Ash from a seven-mile-high column drifted over Anchorage and forced flights to avoid the skies over Cook Inlet.