More than 500 people have been evacuated from the slopes of Mount Karangetang, which has been spewing lava and hotclouds on the northern Indonesian island of Siau.

The conditions have forced authorities to raise the area's alert status, with a total of 151 families or 564 people being evacuated from three villages on the slopes of the 1,784-metre volcano.

Lava and hot clouds emerged from the peak of the mountain on Friday, the Indopos newspaper quoted Sitaro district chief Idrus Mokodompit as saying.

Officials of the vulcanology office could not be immediately reached by telephone on Sunday, but the office's website says the alert status on Mount Karangetang has been raised to one rung below the top level.

Mr Mokodompit says people living in the immediate danger zone on the higher slopes of Mount Karangetang have been evacuated to safer villages on the island.

Hotclouds from the volcano - clouds of high temperatures that slide down the slope at high speed, burning everything in their path - killed three when it last erupted in 1997.

Five years earlier, hotclouds left seven people dead.