Rescue workers have recovered the body of a third Singaporean naval officer following what has been described as the worst naval incident in modern Singapore's history.
A fourth sailor is still missing, after a collision between a patrol boat and a container ship late on Friday.
The four, all women, are believed to have been asleep in their quarters at the rear of the navy vessel, which was crushed in the collision with the Dutch-registered freighter in the Singapore Strait.
As investigations continue into the cause of the accident, salvage workers have begun an operation near the site of the incident to recover a large metallic object, believed to be part of the patrol boat's stern that was wrenched off by the impact.
The bodies of 1st Sergeant Seah Ai Leng, 25, Sergeant Heng Sock Ling, 24, and Corporal Goh Hui Leng, 22, were found over the weekend.
Divers found the body of Goh Hui Leng lodged between the bunks on the vessel, and the bodies of the other two women were washed up on the Indonesian resort of Bintan, south-east of Singapore.
Hopes fade
Officials said they held little hope of finding the fourth sailor, 2nd Sergeant Chua Bee Lin, alive.
The women's ship, the RSS Courageous, a 500-ton Singaporean anti-submarine patrol boat, was towed to Singapore's Changi Naval Base on Saturday.
The cargo ship, the ANL Indonesia, which was en route to South Korea, sustained only minor damage and has been anchored in Singapore pending an investigation.
"The collision was the most terrible accident," Deputy Prime Minister and Defence Minister Tony Tan said after inspecting the damaged ship.
"In terms of the possible loss of life, this is the largest loss of life from a single accident that the RSN (Republic of Singapore Navy) has encountered so far," he said.
The accident happened minutes before midnight on Friday, about one nautical mile (1.8 kilometres) north of Pedra Branca, an islet claimed by both Singapore and Malaysia.
Pedra Branca lies off peninsular Malaysia's southern coast, strategically situated at the eastern entrance of the Singapore Strait.
Eight of the 44 crew on the Courageous were injured. There were no injuries on the ANL Indonesia.