Indonesian scientists are closely monitoring a smoking volcano popular with tourists on Java island and are urging everyone to stay off the mountain's slope, The Associated Press reports.

Government volcanologist Hendra Gunawan said Thursday that Mount Tangkuban Perahu in West Java province has spewed smoke and ash nearly 500 meters (1,640 feet) into the air since Monday. Scientists have put it on the second-highest alert level.

Debris and lava have not tumbled far, and nearby towns and villages remain safe. Authorities are warning tourists to stay at least 1.5 kilometers (1 mile) away from the crater because of the poisonous gas inside.

The 2,084-meter (6,837-foot) volcano is among Java's most popular tourist attractions. It last erupted in 1983. Visitors ordinarily can hike to the crater's edge to view boiling mud up close.