It happened on Sunday at 0700 GMT and involved the 56,686-dwt bulker Sunny Horizon (built 2012) and the 5,000-cbm LPG ship DL Salvia (built 2008).
The bunker tank on the Korean-flagged DL Salvia was said to have been breached and about 60t of bunkers were spilled.
The incident took place about 700 metres east of Sultan Shoal and the area of the spill is within Temasek Fairway.
Local authorities said a patrol craft was sent to the scene, while oil spill response companies were also activated to augment the patrol craft.
The Maritime and Port Authority of Singapore (MPA) said it is investigating the cause of the collision.
Work is continuing and MPA is co-ordinating the clean up with other government agencies and the ship owners.
Seven patrol and anti-pollution craft have been deployed to clean up the spilled oil. There is no report of injury and port operations remain unaffected.
The MPA said the two vessels involved in the collision are now safely anchored in the West Jurong anchorage.
It has issued navigational broadcasts to ships to navigate with caution when in the vicinity of the incident site.
The Sunny Horizon is managed by IMC Group’s MSI Ship Management, while the DL Salvia is owned by South Korea’s Daelim Corp.
In February, TradeWinds reported that Shell had chartered the DL Salvia for two years’ trading at some $285,000 per month.
