JAKARTA (Reuters) - Indonesian authorities on Friday said an Islamic State-inspired militant who injured three police officers this week on the outskirts of the capital, Jakarta, had prepared several pipe bombs and owned live ammunition and weapons.

Thursday's attack was the latest in a series of incidents linked to Islamic State in the world's largest Muslim-majority nation this year, as concerns grow over a resurgence in homegrown militancy.

Police found bomb-making materials, live ammunition, and a samurai sword during a search of the militant's house, a national police spokesman said.

"He had prepared several of those pipe bombs," the spokesman, Boy Rafli Amar, told a news conference. "We are now investigating who he has been in communication with."

Islamic State on Friday claimed responsibility for the attack, through its news agency, Amaq.

The attacker, who stabbed three police officers and threw a pipe bomb that failed to detonate, was shot and died of his wounds.

Police confirmed the attacker, Sultan Aziansyah, was a member of Indonesian militant group Jamaah Ansharut Daulah, which supports Islamic State.

The umbrella group, formed last year through an alliance of splinter groups backing Islamic State, is led by jailed Islamist cleric Aman Abdurrahman, who is serving a nine-year prison sentence for aiding a militant training camp.

Authorities believe Islamic State has more than 1,200 followers in Indonesia and nearly 400 Indonesians have left to join the group in Syria.

Police are on the alert for any Indonesians who return home after Iraqi forces this week launched an offensive to take back the Islamic State stronghold of Mosul.

Authorities are monitoring about 40 of those who returned, concerned they could be linking up with existing networks, police chief Tito Karnavian told Reuters on Monday.

In January, four militants mounted a gun and bomb attack in the heart of Jakarta, the first attack in Southeast Asia claimed by Islamic State. Eight people were killed, including the militants.

(Reporting by Fergus Jensen; Writing by Kanupriya Kapoor; Editing by Clarence Fernandez)