The Australian embassy in Indonesia is among several warning that extremists may attack the Miss World beauty pageant on the resort island of Bali after a series of hardline Muslim protests.
The US and British embassies have also issued warnings to citizens in recent days.
"The embassy has received information that extremist groups may be planning to disrupt the Miss World pageant being held in Bali from September 8 to 28, potentially through violent means," the US embassy in Jakarta said in a statement.
Meanwhile, the British embassy said "local Islamist vigilante groups have threatened to hold large-scale demonstrations to disrupt the Miss World pageant".
It added that "extremist groups may also be planning to attack the event".
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Bali has been attacked by Islamic militants before, most notably in 2002 when bombings on the resort island killed 202 people, many of them foreigners.
However, Indonesia, which has the world's biggest Muslim population, has waged a crackdown on militant groups over the past decade and has succeeded in dismantling key networks.
In recent weeks thousands of radicals have taken to the streets protesting against the decision to hold Miss World in Indonesia, denouncing it as "smut" and "pornography".
The growing protest movement prompted the government to order the entire event be moved to Hindu-majority Bali, where extremist influence is minimal.
Originally only the early rounds were due to take place on the island, with later rounds and the September 28 final to be held in and around the capital Jakarta.
While the vast majority of Indonesians practise a moderate form of Islam, a vocal hardline fringe has become increasingly influential in recent years.
