Four Indonesians were rescued in the waters near Pedra Branca by Singapore's Police Coast Guard (PCG) and navy after the men jumped from a stalled motorised boat early yesterday morning.
The Maritime and Port Authority of Singapore (MPA) said yesterday that it received a report on the incident at 2.53am.
The boat was about 0.7 nautical mile north-east of Pedra Branca, within Singapore territorial waters, the MPA said in a statement.
The men were part of a group of more than 100 people - including 22 women, two of them pregnant, and four children - believed to be illegal migrants working in Malaysia and making their way back to their home towns when the boat ran out of fuel, Indonesian media reported.
They were later transferred to an Indonesian Marine Police vessel that took them to Batam, where they were held for questioning.
The MPA said one person is still unaccounted for, and that according to those rescued, there was a total of 108 people on board the boat.
It has also issued navigational broadcasts for ships to look for the missing person, and Singapore is coordinating search-and-rescue operations with the Indonesian authorities.
The Straits Times understands that two navy patrol vessels, the RSS Freedom and RSS Daring, as well as three PCG vessels were deployed for the search-and-rescue operations.
However, Indonesian police said that all the passengers aboard the boat are safe. Colonel Saptono Erlangga, Riau Islands province police spokesman, said no one is missing.
Defence Minister Ng Eng Hen posted an image of the passengers aboard their packed boat on Facebook, and said Singapore's Maritime Security Task Force, operating off Changi, had spotted a motorised boat which had lost power and was drifting around the waters off Pedra Branca.
The task force sent a PCG vessel to investigate.
"Some were seen to have jumped overboard from the stranded boat and were swimming away," he said.
"Subsequently, both PCG and the Republic of Singapore Navy crew picked up four of them in the water and transferred them, as well as the rest of the passengers on the boat, to the Indonesian police," he added, thanking the agencies involved for their professionalism and alertness in guarding Singapore's waters round the clock.
Riau Islands provincial police yesterday released photos of the passengers being transferred and ferried to land.
Barelang police chief Hengki told reporters: "They came from Malaysia, ran out of fuel and drifted out to sea. They were heading home to see their families."
Many of the passengers are migrant workers whose passports have expired, and they had paid smugglers up to RM1,500 (S$510) each to cross borders illegally, Indonesia's Kompas newspaper reported on its website.
A worker who identified herself only as Risma, from Surabaya, told reporters: "We were in the jungle for four days before we left Malaysia on a boat. But after a few hours, the boat engines stopped."
Indonesian media reported that the passengers were transferred to Indonesian police vessels at about 9am, and all are in stable condition.
Antara news agency noted that ahead of the fasting month each year, thousands of illegal Indonesian workers in Malaysia try to make their way home by sea. Some head in the other direction.
On Tuesday, 40 Indonesians looking to migrate illegally, four crew members and nine Bangladeshi nationals were detained in Batam for trying to cross to Johor illegally on a motorised boat, Antara reported.