Philippine Coast Guard personnel collect water samples from an oil spill in the waters off Naujan in Oriental Mindoro province after the sinking of a tanker carrying 800,000 liters of industrial fuel oil (AP).

A tanker that carried some 800,000 liters of industrial fuel partially sank on Tuesday in the waters off the Philippines coast and caused the oil onboard to spill.

The spill expanded to reach approximately 24 square kilometers away from The Philippines' coast, which is threatening the local marine life, according to media reports on Thursday.

The oil spill may impact 21 marine protected areas, according to the Philippine Department of Environment and Natural Resources (DENR).

"On a maximum of 40-kilometer [25-mile] radius from 5 nautical miles east of Balingawan Port, 21 locally-managed marine protected areas can be potentially affected due to oil spillage," the DENR said in a statement.

In parallel, the governor of the Oriental Mindoro province, Humerlito Dolor, stated that the oil spill zone is growing.

"The 6 by 4-kilometer affected area seems to be getting even wider," Dolor said, as quoted by ABS-CBN.

According to the report, the Philippine Coast Guard has put oil containment fences and dispersants in the sea. The authorities also vowed to assist nearby fishermen who are unable to catch fish as a result of the disaster.