Currently there are about 5000 Socceroo fans in Thailand for the Asian Cup. The final of the tournament will be played in Jakarta, Indonesia, on July 29. Australia is currently playing in the group stages but is considered one of the favourites to make the final in three weeks time.

The Department of Foreign Affairs and Trade reissued its travel advisory for Indonesia, saying terrorists are actively planning attacks which could take place at any time.

Howard said travel advisories are only issued on strong intelligence. "All terrorist threats are serious and the problem is if you don't warn of them and something happens you are legitimately criticised," he told Channel 9.

Foreign minister Alexander Downer said soft targets like the nightclubs of Bali can often be targeted by terrorists looking to inflict maximum fatalities while avoiding high security areas. "Those locations where westerners tend to concentrate can often be targets,” he said.

Attorney-General Philip Ruddock said on ABC radio, "The fact is we've seen what's happened in Indonesia before - the concern we have remains because people we know are involved in the planning of previous bombings, Noordin Top in particular, remain at large.

"When you receive information that suggests they're still engaged in planning such attacks, you can't just put it to one side."

For up-to-date travel advisaries for all Asian Cup countries head to www.smartraveller.gov.au.