INCHEON (Yonhap News) -- Efforts are under way to clean up diesel fuel that leaked into the Yellow Sea early Wednesday from a fuel storage facility of a front-line Marine base, military officials said, noting no major damage was reported from oil spill.

The 6th Marine Brigade based on the northern island of Baengyeong said a sergeant reported the diesel spill at around 7:20 a.m, estimating some 25,000-30,000 liters of diesel were missing from the fuel storage.

Baengnyeong is located just south of the Northern Limit Line (NLL), a de facto maritime border between the Koreas.

Clumps of oil from the leak have been found in the sea over a radius of 200 meters as well as the nearby coastline about 1.5 kilometers away, officials said.

Authorities suspect the oil leak occurred during the process of changing the old pipeline, which began on Monday.

The Marine Corps said they have set up oil fences to prevent the spill from spreading further into the sea, mobilizing some 700 emergency workers, excavators and patrol boats.

Due to the accident, residents gave up on fishing for the day.

Marine officials said no major damage has been reported by residents so far and that they will soon recover the oil that spilled into the sea.

"Because it is diesel, it will evaporate as time passes," a Marine official said. "We are putting forth our utmost efforts to prevent further damage."