Divers looking for 10 missing sailors on a US navy guided-missile destroyer that collided with an oil tanker off Singapore have found human remains, a US admiral said on Tuesday.

The accident on Monday, which left a gaping gash in the destroyer's hull, was the second deadly collision in two months involving an American warship.

The US Navy has announced a fleet-wide global investigation after the accident involving the USS John S McCain and the merchant vessel.

Bodies were discovered in the parts of the US ship that were sealed off after the crash. Malaysian navy crews taking part in search efforts also found a body outside the vessel.

The remains are in the process of being identified, Pacific Fleet Commander Admiral Scott Swift told reporters in Singapore, where the USS John S McCain was brought to after the collision in the waters east of the city-state.

"We owe it to sailors that man the 7th Fleet and their families to answer the questions that flow from the uncertainty of what happened, how could it happen and what could be done to prevent such occurrences in the future," Swift said.

Four of the five injured sailors were airlifted to hospital in Singapore for non-life-threatening injuries, while the fifth required no further medical attention.

The Alnic MC tanker, which transports oil and chemicals, sustained damage but the crew escaped unharmed. A shipping company based in the Greek capital Athens, Stealth Maritime, operates the tanker.

'Comprehensive review'

It was the second fatal collision in two months - after the USS Fitzgerald collided with a Philippine-flagged cargo ship off Japan in June and left seven sailors dead - and the fourth accident in the Pacific this year involving an American warship.

The incidents have sparked concern that the US Navy could be overstretched in East Asia - both ships were from the Japan-based Seventh Fleet - as they tackle China's rising assertiveness and North Korea's nuclear ambitions.

The McCain had been heading for a routine stop in Singapore after carrying out a "freedom of navigation operation" in the disputed South China Sea earlier in August, sparking a furious response from Beijing.

On Monday, the Chief of US Naval Operations Admiral John Richardson ordered commanders within a week to set aside time, perhaps "one or two days", for crews to sit down together for discussions.

A "comprehensive review" of practices would also begin.

"As you know, this is the second collision in three months and the last of a series of incidents in the Pacific theatre," Richardson said.

"This trend demands more forceful action. As such, I have directed an operational pause be taken in all of our fleets around the world."

The damaged vessel is named after US Senator John McCain's father and grandfather, who were both admirals in the US navy.