Clouds of volcanic ash from an eruption off the Pacific nation of Tonga have reached Australia, more than 3,000 kilometers west of their source. Local aviation authorities are calling on airlines to be on a high alert.

Australia's volcanic ash advisory center in Darwin says that ash clouds have reached the country's northeast. Center officials say satellite images and reports from aircraft indicate that clouds of ash are moving westward at an altitude of between 12 and 19 kilometers, with a speed of about 92 kilometers per hour.

The officials forecast that ash clouds will blanket the northern half of the country on Tuesday morning.

The advisory center has issued the second highest of its four alert levels for flights in the region.