Indonesia's most wanted terror suspect had been planning attacks on the Danish embassy and a police ceremony before his arrest, media reports and officials say.
Bomb-making material and revolvers were seized from his rented home.
Abdullah Sunata and two of his aides were taken into custody on Wednesday following a series of coordinated raids in Central Java province.
Tito Karnavian, who heads the anti-terror squad, said on Friday Sunata allegedly wanted to bomb the Danish embassy over anger about a Danish newspaper's publication of cartoons depicting Islam's Prophet Muhammad, The Jakarta Globe newspaper reported.
Officials refused to confirm that on Friday, saying only that an unnamed European mission had been a target. But members of the Danish Security and Intelligence Service were heading to Indonesia's capital, Jakarta, to help reinforce security at their embassy.