Jakarta attack could have been much worse

The deadly terrorist attack in the centre of Jakarta confirms the growing threat Islamic State poses in Indonesia, but the outcome could have been much worse.

Indonesia specialist Greg Fealy, from the Australian National University, says that if the perpetrators had been more efficient terrorists, many more people might have been killed.

IS and the war in Iraq and Syria have been a source of inspiration for violent jihadists in Indonesia, but Thursday's attack was the first larger-scale effort claimed by the group in the world's most populous Muslim nation.

At least seven people were killed and dozens injured when the militants attacked a police post near a shopping mall in an affluent area of the capital, and set off multiple blasts including a suicide bomb near a Starbucks cafe.

IS has claimed responsibility, saying the attack was carried out by a detachment of its forces in Indonesia who "targeted a gathering of crusader coalition citizens".

The outcome could have been much worse, Associate Professor Fealy told AAP.

"It was very crude. And the perpetrators looked like amateurs."

He said the taking of hostages - one who was Algerian and a fellow Muslim - was "further indication that it was poorly planned and poorly carried out".

"Thankfully, because otherwise if they had been efficient terrorists they could have killed a large number of people in that place.

"If they had in mind a Paris-style attack, well then they've failed dismally at that."

But Associate Professor Fealy said the attack was also evidence of the growing threat posed by IS.

IS-inspired extremists have carried out smaller attacks in Indonesia but Thursday's assault is believed to have been organised from Syria by an Indonesian national identified by police as Bahrun Naim, the leader of Katibah Nusantara, a Southeast Asian group attached to IS.

"It confirms the threat that ISIS poses to Indonesia," Associate Professor Fealy said.

Multiple targets were in Thursday's attack, he said.

"I think the jihadists are always very keen to kill police whenever they can and the fact that they blew up that police post was an indication of that.

"But they also clearly would like to target Westerners and to target elite Indonesians, and attacking the spot that they did yesterday served all of those purposes for them."