Some of the Indonesian men arrested at the weekend after tip-offs that they were planning a string of militant attacks had received funding from Syria, hardening evidence of their links to Islamic State, police said on Monday.
Officials said the raids in five cities across the island of Java, during which nine people were detained and bomb-making equipment was seized, may have foiled plans to target New Year celebrations.
Police said they remained on high alert, underlining concern about a resurgence of militant attacks by Indonesians who have returned from fighting with the radical Islamic State group in Syria.
"They received transfers of funds ... they have a connection with Syria," national police spokesman Anton Charliyan told a news conference.
"What we gather so far is they are linked to the ISIS group," he said, using a common acronym for Islamic State. "They got the money from a senior ISIS figure who works as a coordinator to link ISIS to Indonesia."