Ashes from Mount Ruang are predicted to reach Malaysian airspace and have a substantial impact until May 5, according to MetMalaysia.
It is predicted to have an impact on operations in the Kota Kinabalu Flight Information Region. MetMalaysia has issued a SIGMET alert to aircraft operators.
On Wednesday morning, Indonesia's meteorology ministry posted a map showing that volcanic ash from Mount Ruang had spread as far as East Malaysia.
In the meantime, officials said that more than half of the Indonesian airports had to close due to volcanic eruptions.
Due to tsunami worries, thousands are being evacuated from Tagulandang island north to Siau island.
On Wednesday morning, Julius Ramopolii, head of Mount Ruang's monitoring site, stated that the volcano was still billowing ash and smoke over the crater.
"The volcano is clearly seen, the plume of smoke is visible, grey and thick, and reached 500-700 meters above the crater," he added.
He explained that the warning level remained at the highest of a four-tiered system and urged residents to stay outside of a 7-kilometer exclusion zone.
Source: BFM News X