Bali earthquake: Fears of volcanic eruption on popular tourist island as 5.7-magnitude tremor strikes

Authorities evacuate area around Mount Agung, a well-known hiking destination

The location of the overnight earthquake in the Java Sea (USGS)

Fears of a volcanic eruption on the Indonesian island of Bali have been triggered by a large earthquake nearby.

A 5.7-magnitude tremor was detected in the Java Sea late on Wednesday, the US Geological Survey said, at a depth of 589km.

Officials had already widened an evacuation zone around the 3,000m-high Mount Agung volcano earlier in the week, according to reports.

Seismic activity around the mountain increased dramatically on Monday, forcing authorities to put residents on high alert and to evacuate those within 7.5km of the volcano, ABC reported.

Mount Agung is a popular hiking destination for tourists. It last erupted more than 50 years ago, killing at least 1,000 people.

"This is a natural disaster, we cannot avoid it, we can't stop it exploding but we can reduce the number of victims and losses. We are prepared, I believe we can handle everything," Governor Made Mangku Pastika told the site.