Indonesian police on Saturday named the five men they suspect launched this week's gun and bomb attack in the heart of Jakarta and said they had arrested 12 others linked to the plot, which was claimed by Islamic State.

As investigators pieced together clues from the radical group's first strike on Indonesia, neighbouring Malaysia said it had arrested a man in Kuala Lumpur who had confessed to planning a suicide attack in the country.

"We ... have carried out acts of force. We have done searches, we have made arrests and we have obtained evidence connected with the terrorist bombing at Sarinah," Jakarta police spokesman Mohammad Iqbal told a news conference.

"We will not say how many people or what sort of evidence we have as it will upset out strategy. Be patient, when the case is closed and things are clear we will disclose them."

Seven people, including the team of militants, were killed in Thursday's attack near the Sarinah department store in the Indonesian capital's commercial district. About 30 people were wounded.

Police held up pictures of the dead and wounded at the news conference, including a man who kicked off the siege by blowing himself up in a Starbucks cafe.

Another attacker, who opened fire with a gun outside the cafe, was named as Afif. A National Counter-Terrorism Agency spokesman said Afif had served seven years in prison, where he refused to cooperate with a de-radicalisation programme.

The brazenness of the Jakarta assault, which had echoes of marauding gun and bomb attacks such as the Paris siege in November, suggested a new brand of militancy in a country where extremists typically launch low-level strikes on police.

MALAYSIAN PLANNED SUICIDE ATTACK

In Malaysia, the country's police chief said that a suspected militant who was arrested in a metro station in Kuala Lumpur on Friday had confessed to planning a suicide attack.

Inspector-General of Police Khalid Abu Bakar said in a statement that the 28-year-old Malaysian confessed to planning a suicide attack in the country after receiving orders from a foreign member of Islamic State (IS) in Syria.

"The suspect is also responsible for hanging IS flags at several locations ... to warn the government to stop arresting IS members in Malaysia," Khalid said.

No details were given on where and how he planned to attack.

Khalid said three other people suspected of being supporters of Islamic State were arrested this week at Kuala Lumpur airport after they returned from Turkey.

Malaysia has been on high alert since Thursday's siege in Jakarta. Security has been beefed up in public areas and borders have been tightened to prevent jihadis getting into the country.

Earlier on Saturday, Indonesia said it had shut down at least 11 radical websites and several social media accounts, including several on Facebook that expressed support for the Jakarta attack.

"We are monitoring many websites and public complaints about this," said Ismail Cawidu, a public relations official at the communications ministry.

The government had also sent letters to social media companies such as Facebook, Twitter and Telegram requesting that radical material be immediately blocked or taken down, Cawidu said.

The alleged mastermind behind the Jakarta attack, an Indonesian citizen fighting with Islamic State in Syria, is believed to have used social media extensively to share his beliefs about the group and communicate with contacts in Indonesia using blog posts and mobile messaging apps.

Authorities believe there are at least 1,000 Islamic State sympathisers in Indonesia, which has the world's largest Muslim population.-Reuters