Thais have been warned not to travel to the northern part of Bali following rumblings from the Mount Agung volcano, which is threatening to erupt.
Indonesian authorities on Friday raised the volcano's alert status to the highest level following a "tremendous increase" in seismic activity. Its last eruption in 1963 killed 1,100 people.
At least 34,000 people have fled the areas around the volcano on the resort island as tremours increase, sparking fears it will erupt for the first time in half of century.
There are 30-40 Thai nationals living in Bali, according to the Thai embassy in Jakarta. Most of them live in the downtown area 3-4 hours' travelling time from the volcano, it said.
Tour agencies said they are watching developments on the island closely. Trips will be postponed or shifted to other destinations if conditions there worsen, they said. They said no group tours had been cancelled.
Operators including Mira Ontour, Thoongtong Tour and Best Tour Holiday said several tourists had postponed their plans to visit northern Bali, but those who had booked trips to other parts of the island planned to continue with their trips.
Most Thai tourists will visit lakes and cultural sites on the western side of the island, a safe distance from the volcano, they said.
"Only a few tourists want to visit places nearby the crater, and they should postpone those trips," said a staff member from Mira Ontour.
Indonesia's National Disaster Mitigation Agency issued a travel warning saying no one should be within 9km west of the crater and 12km to the north, east and south, in case the volcano erupts and lava starts to flow in those directions.
Dodo Sudradjat, the minister for information and socio-cultural affairs at the Indonesian embassy in Bangkok, said most tourism destinations in Bali are located a safe distance from Mount Agung.
The eruption warning has not affected tourism on the island significantly, he said, but local authorities are making necessary preparations in case an emergency occurs. "I think tourists in Bali or those who plan to visit Bali should monitor the situation," Mr Sudradjat said.
Tourist attractions in the rest of the country are open as usual.
Mr Sudradjat said nearly 100,000 Thai tourists visited Indonesia last year. The most popular destinations for Thais are Bali followed by Jakarta.
More than 200,000 Thais are expected to travel to the archipelago nation this year. The number is expected to surge next year when it hosts the 2018 Asian Games from Aug 18 to Sept 2.
Indonesia welcomed 2.5 million international arrivals in 2015 and 3 million last year. The number is expected to reach 5 million in 2018.
In turn, about 470,000 Indonesian tourists visited Thailand in 2015 and 536,000 in 2016. The Tourism Authority of Thailand said numbers from Indonesia continue to grow this year.
In 1963, the 3,000m Mount Agung hurled ash as high as 20km and remained active for about a year. Lava traveled 7.5km and ash reached Jakarta about 1,000km away.
Tourists flocks to Bali to surf, enjoy holistic retreats in Ubud and sample Kopi Luwak coffee, among other excursions.
