Singapore's port waters have been cleaned significantly since mop-up operations of recent oil spills commenced, said the Maritime and Port Authority of Singapore (MPA) on Tuesday.
Two vessel collisions on Jan 29 and 30 had resulted in oil spills south of Jurong Island and off Marina South respectively.
In a statement, the MPA said: "The clean-up efforts have resulted in significant improvements to Singapore's port waters, except for minor oil patches in the vicinity of the Southern Islands, and a few patches of oil at Pulau Seringat shoreline which are being removed by response craft and personnel using oil booms and skimmers.
"MPA continues to work closely with the National Environment Agency and the Sentosa Development Corporation on the landward clean-up operations."
When The Straits Times visited Kusu and St John Islands on Tuesday, workers could be seen shovelling oil-slicked sand into garbage bags and carting the bags from the affected beaches to the ferry points.
The spillages resulted from a collision on Jan 29 between Hong Kong-flagged chemical tanker Lime Galaxy and China-flagged containership Feihe at about 2.7km south of Jurong Island, and another one on the next day between Panama-flagged containership NYK Themis and a barge, AZ Fuzhou, at the East Keppel Fairway about 4km south of Marina South.
The MPA, which is coordinating the containment and clean-up operations, said it is monitoring the port waters for undetected patches of oil.
The authority added that neither vessel traffic in the Strait of Singapore or port waters have been affected, and that investigations into both incidents are ongoing.