The FCDO warned against travel to within 3km of the crater in West Sumatra, within 5km of the Mount Sinabung crater in North Sumatra and within 5km of the crater of Mount Semeru in East Java.
Brits are also advised against travelling to the southeast area of Mount Semeru along the Besuk Kobokan river.
The FCDO highlighted how travel insurance could be invalidated if your customers were to travel against FCDO.
Marapi spewed a 3km ash cloud into the air, blanketing surrounding villages in ash, just over a week ago. There have been other eruptions subsequently.
The BBC reported that there were 75 hikers in the area during the main eruption on 3 December.
Marapi is among the most active of Indonesia’s 127 volcanoes and is also popular among hikers.
