Jakarta - Indonesian authorities on Thursday urged residents living around the slopes of Mount Semeru in Indonesia's crowded East Java province to keep their distance from the active volcano, which appears to be heating up.

Vulcanologists upgraded the alert status of Mount Semeru volcano to level three, one level below a full state of alert, after the 3,676-metre-high volcano on Wednesday sent hot lava as much as 3,000 metres down its slopes.

Villagers and farmers were urged "not to conduct activity at a radius of 4 kilometres from the crater, especially around the south-east of the volcano's slopes," said Surono, head of Indonesia's Centre for Volcanology and Geological Hazard Mitigation at the directorate general of volcanology.

Surono, who like many Indonesians goes only by one name, appealed to residents living on the riverbanks along three different rivers to be cautious of threats posed by lava streams.

However, no immediate evacuation is being considered for residents living in a number villages in the potential danger zone, he said, adding that a team of experts is intensively monitoring Mount Semeru's activity round-the-clock.

The Mount Semeru volcano, 780 kilometres east of Jakarta, is a popular tourist destination, especially for hikers. Semeru is one of Indonesia's most active volcanoes.

The Indonesian archipelago, straddling the seismically active "Ring of Fire," has the world's highest density of volcanoes. Of its 500 volcanoes, 128 are active and 65 are listed as dangerous. (dpa)