Nearly 50,000 people on Indonesia's resort island of Bali have sought refuge in temporary shelters, as fears grow that Mount Agung could erupt for the first time in half a century, the Deutsch Presse-Agentur, DPA, has reported.

"Officials denied false news circulating online that the volcano had already erupted, saying photos on social media were from previous volcanic eruptions in the country," added DPA.

"Mount Agung hasn't erupted," said Sutopo Nugroho, spokesman for the National Disaster Management Agency, adding that the images are of different volcanoes.

Authorities on Friday raised the alert for Mount Agung to the highest level, indicating an eruption is imminent.

Budi Hartini, an official at an emergency post in Karangasem district, where the volcano is located, said that 49,300 people living near the volcano had been sheltered in makeshift camps in 10 localities.

"There are still villagers who are staying put and we are persuading them to evacuate," Hartini said.