"On Tuesday the activities of Mount Semeru started increasing, until on Wednesday there was an eruption, but not too large," Heri Subagiaji, head of the Bromo Tengger Semeru National Conservation Park, told AFP.

No one was injured in the eruption which spewed debris over a radius of 700 metres (770 yards), the volcano's first emission of debris in "a rather long time," said Subagiaji, speaking from the city of Malang, close to the volcano.

"There is still potential for disaster," Subagiaji said. "For the moment it is closed."

However, residents in the area have not been ordered from their homes, he said.

In June the nearby Mount Bromo, a popular tourist destination, shot out a shower of rocks and stones which killed a 13-year-old Singaporean boy and an Indonesian.

Indonesia sits on the "Pacific Rim of Fire" noted for its volcanic and seismic activity. The country has more than 100 active volcanoes.

Last week officials on the island of Sumatra banned hikers from the popular Mount Kerinci following an increase in volcanic activity.

TERRA.WIRE