KUPANG (Indonesia) - SEVENTY-FOUR Afghan migrants are missing after their boat sank in treacherous Indonesian waters, a maritime official said on Wednesday, citing a tip-off from Australian police.

The boat sank late Tuesday in the Sape Strait off Komodo island, a nature reserve for deadly komodo dragon reptiles, Labuhanbajo port chief Pariman said on eastern Flores island.

He said Australian police had alerted their counterparts in Flores's West Manggarai regency that the boat was missing, but a search of nearby waters and Komodo island had found no trace of the Afghans.

'We don't know where the vessel departed from or its destination. We don't even know the name of the vessel,' he told AFP. 'A patrol team consisting of navy and sea police started searching for them this morning with no result. We've also searched on the coast of Komodo island.'

Sape Strait is a deep and narrow channel known for strong currents and swirling rips which frequently trouble experienced scuba divers visiting the famous dive sites in the area.

A group of divers from Europe were carried away from their boat last year and drifted for about eight hours before finally washing up on Komodo island and spending a tense night surrounded by dragons.

Mr Pariman said it was strange there had been no sign of the Afghans.

'Even the fishermen and ships in the area didn't see the Afghans. It's strange because the strait between West Nusa Tenggara and East Nusa Tenggara is busy with sea traffic,' he said.

He said the search would continue on Thursday.

Indonesia is a transit route for migrants seeking to travel to Australia in rickety boats with the help of people smugglers. Indonesian authorities work closely with their Australian counterparts to try to stem the flow of illegal immigrants. -- AFP