One of the suspected terrorists during the fatal attack in Jakarta on in January. Credit:AP "This is of grave concern for Australia and the Australian government. We are working in close co-operation with our neighbours to keep the region safe from terror." Mr Keenan has been to Indonesia three times since becoming justice minister, with the discussion mainly centred around shared counter-terrorism efforts. Australian and Indonesian authorities have a history of strong cooperation in the field, with Australia supporting Indonesia in the investigation of several major terrorist attacks in Indonesia, resulting in arrests and convictions. Indonesian authorities have proven highly effective in disrupting terrorist plots and networks. There have been more than 900 terrorism-related arrests and about 650 convictions since 2002.

People carry an injured police officer near the site where an explosion went off at a police post during the Jakarta attacks. Credit:AP "Recent indications suggest that terrorists may be in the advanced stages of preparing attacks in Indonesia," the smartraveller website entry for Indonesia says. However the overall level of advice for the country has not changed. The site of terror attacks in Central Jakarta in January. Credit:Screengrab "We advise you to exercise a high degree of caution in Indonesia, including Bali," it says.

Security in Bali has been immediately increased following the warning, with police and military personnel patrolling the airport. The Australian forensic officers from look for evidence Bali bombing site in 2002. Credit:Kate Geraghty Bali airport authority head Yusfandri Hona told Fairfax Media the authority was also conducting background checks on airport staff. "We have further increased security throughout the airport in response to the travel warnings," he said after a meeting held to discuss threat. Mr Yusfandri said this was on top of the high security alert put in place after the January 14 attacks.

Terror expert and chair in Global Islamic Politics at Deakin University Greg Barton said he suspected Australian authorities had intercepted communications that showed increased "chatter" that was cause for concern. "When they intercept communications they might not necessarily get access to the contents of the message but may see an increase in frequency between two nodes of concern," Professor Barton said. He said messaging services, such as Telegram, may contain encrypted messages but a flurry of activity could indicate imminent attacks. "Some times places and times also come up in unencrypted messages," he said. Professor Barton said prior to the 2002 Bali bombings the American Embassy had issued warnings of possible attacks in places such as Bali.

He said the Australian government had been criticised after the bombings for not having done so: "The position now is it is better to be safe with public communication." The warning comes after the Australian government also warned of a possible attack in the Malaysian capital Kuala Lumpur on Sunday, indicating Australian agencies have received specific information about a potential terrorist plot. Malaysia later said it was not aware of what might have prompted such a warning. Indonesia is currently debating measures to tighten its anti-terror laws passed after the January 14 suicide bombings and shootings in Central Jakarta, which left eight dead. "We can detect a terrorist network but we can't act before they have committed a crime," said national police chief Badrodin Haiti. "That is the weakness of our laws."

The draft legislation, seen by Fairfax Media, says an individual could be detained for up to six months if it was suspected they would carry out an act of terrorism. It would also become an offence to join a terrorist group such as Islamic State, or recruit others, with a maximum punishment of seven years' jail. The Bali police and airport authority convened meetings immediately after the updated warning from Australia. National police spokesman Agus Rianto told Fairfax Media Indonesia was safe and security was under control. "It is understandable if people are worried however [special forces police unit] Detachment 88 continues to chase people based on interrogations of people arrested recently," Mr Agus told Fairfax Media.

About 40 people have been detained in connection with the police probe to uncover the network of those involved in the Jakarta attacks. Mr Agus said bombmaking materials such as nails and fertiliser had been found during the arrests. "The President [Joko Widodo] said we are not afraid, however we remain alert," he said. "The police along with related agencies and the people are working together to monitor the situation to make sure the security is there." Foreign Minister Julie Bishop said the Australian government worked closely with the Indonesian government to address terrorism. "It is a shared threat," she said.

"I urge all Australians travelling, whether to Indonesia or elsewhere, to purchase travel insurance, register on smartraveller and to read the travel advice carefully before they travel." Follow FairfaxForeign on Twitter Follow FairfaxForeign on Facebook