Singapore authorities said Monday a dredger boat reported a sudden loss in engine and steering control that led it to hit a stationary cargo tanker, causing an oil spill that has blackened part of the city island's southern shores.

The Netherlands-flagged dredger Vox Maxima struck the Singaporean fuel supply ship Marine Honor on Friday. It ruptured one of the cargo tanks on the Marine Honor, which leaked low-sulfur oil into the sea. Although the leak has been contained, tides washed the spilled oil that had been treated with dispersants further along the shoreline, including to the popular resort island of Sentosa.

Singapore's Maritime and Port Authority, in a joint statement with the National Environment Agency, the National Parks Board and Sentosa Development Corp., said the master and crew members of Vox Maxima are assisting in the ongoing investigations.

Part of the beachfront at a public park, beaches at three southern islands and a nature reserve have been closed to facilitate cleanup efforts. Sentosa beaches remain open to the public but sea activities and swimming are prohibited.

Oil Spill Response Limited, an industry-funded cooperative that responds to spills, will deploy floating containment and recovery devices to corral the oil on the water surface, where two skimmer craft will then lift the oil into storage tanks, the statement said.

Over 250 workers are involved in the cleanup. Close to 1.5 kilometers (.9 miles) of containment booms have been set up to trap the oil and another 1.6 kilometers (1 mile) of temporary barriers will be laid over the next few days to prevent further spread of oil onto the shore, the statement said.

The National Parks Board also deployed oil-absorbing booms to protect mangroves at another park that hasn't been affected so far. Members of the public who volunteered to help have been assigned to patrol the park for early signs of oil slicks.

Conservationists and biologists are monitoring the full extent of the damage to marine and wildlife. Photos in Singapore newspapers and on Facebook showed one small dead fish and a kingfisher covered in oil.