ANCHORAGE, Alaska (REUTERS) - One of Alaska's most active volcanoes, which has been belching ash and spewing lava since last week, has forced regional flight cancellations and dusted some nearby communities with ash, scientists and local officials said on Monday.

Pavlof Volcano has sent up ash as high as 6,700m, with the cloud blowing eastward and the eruption showing no signs of abating, according to the federal-state Alaska Volcano Observatory.

The lava from 2,518m peak has also created huge steam clouds on meeting the mountain's snow.

While the ash plume was still too low on Monday to affect commercial airliners flying at least 9,150m above sea level between Asia and North America, it was scrambling schedules for regional carriers serving rural fishing towns and native villages that lack outside road access.

PenAir, an Anchorage-based Alaska company specialising in travel in south-western Alaska, briefly stopped flights to four destinations to wait for ash to dissipate, said Mr Danny Seybert, the carrier's chief executive. "We've had about a dozen cancellations due to the volcano," he said.

PenAir's planes fly at altitudes between 4,500m and 6,000m, exactly where they could encounter ash, depending on wind direction, Mr Seybert said.

Among the cancellations were flights in and out of Unalaska/Dutch Harbour, the top-volume seafood port in the United States, he said.

Ash plumes could go higher, as Pavlof's eruption could intensify with little warning, the Alaska Volcano Observatory said.

Trace amounts of ash fell overnight on Nelson Lagoon, a tiny Aleut village of 50 residents located 77km north-east of Pavlof. The volcano had earlier sprinkled ash on Sand Point, a fishing town of about 1,000 people, when the wind was blowing in a slightly different direction, according to the observatory.

Along with potential aviation hazards, the ash poses possible health risks, said Mr Rick Wessels, a US Geological Survey geophysicist at the observatory.

"It's dangerous for the people downwind of it, because you don't really want to breathe in that fine ash that long," Mr Wessels said of the eruption taking place on the Alaska Peninsula, 950km south-west of Anchorage.

Pavlof is one of Alaska's most restless volcanoes and had its last major eruption in 2007. The Alaska Volcano Observatory estimates it has erupted about two dozen times between 1901 and 2007.