JAKARTA - Indonesia's Anak Krakatau volcano located in the waters of Sunda Strait erupted on Tuesday morning, spewing volcanic ash cloud of about 1 km high into the sky, an official said.

The volcano's Observation Post Officer Anggi Nuryo Saputro said the eruption occurred at 6:29 am local time for 130 seconds, with the wind heading north.

"The ash column was observed to be gray to black in color with thick intensity towards the north," he said in a statement.

Since its birth in June 1927, Anak Krakatau's volcanic activity has been on the rise, making its body larger and taller, up to 157 m above the sea level. Its activity has increased significantly since April last year, which raised its dangerous status to the third highest level.

In 2018, Anak Krakatau erupted and triggered a tsunami that killed over 400 people and left thousands homeless.