Indonesian officials confirmed on Friday that up to 32 Indonesians had been detained in Turkey or gone missing after being suspected of trying to cross into Syria to join Islamic State (IS) militants.
Foreign Minister Retno Marsudi told reporters a group of 16 Indonesians, most of them women and children, had been arrested by Turkish authorities this week.
"We have obtained information that they were indeed trying to cross into Syria," she said, adding that Indonesia would send a team to help a Turkish investigation.
Marsudi said 16 other Indonesian citizens who went missing from a tour group last week had yet to be located, adding that Turkish authorities had yet to confirm if they were still in Turkey or had crossed into Syria.
National police chief Badrodin Haiti said on Thursday the groups were suspected of trying to join IS.
Indonesia has the world's largest Muslim population and it has grappled with attacks by a small number of homegrown militants since the early 2000s.
In their most deadly attack, Indonesian militants bombed a nightclub on the holiday island of Bali in 2002, killing 202 people, many of them Australian tourists.
Authorities uprooted most militant cells in subsequent years but the government has raised concern in recent months over Indonesians traveling to Syria and Iraq to join IS.
Officials say between 200 and 300 Indonesians have left the country but some security experts believe the figure is higher.