Experts are '100 per cent sure' that the oil slicks found at South China Sea came from other sources and not from the missing Malaysian Airlines (MAS) MH370 aircraft.

A marine engineer who declined to reveal his identity told Astro AWANI that he had seen many such oil slicks throughout his career.

“While I am not 100% certain that the slick is from a tanker, I am 100% certain that it is not aircraft fuel,” said the source who has 50 years of experience in the ship operating, construction and design industry and has worked on oil tankers.

He said oil slicks such as the one found were more common those days when marine anti-pollution regulations were not as tight as now.

“But, the same anti pollution regulations however, do allow the discharge of aviation fuel direct to sea in emergencies due to its non persistent nature where no clean-up is required,” he added.

He was referring to spills from oil tanks like the Exxon Valdez incident in the American waters in 1989 which was the biggest oil spill incident to the BP oil spill in Gulf of Mexico in 2010.

Malaysia Maritime Enforcement Agency (APMM) had on Sunday confirmed the spotting of two large oil slicks about 20 nautical miles south of where the MH370 aircraft was last detected before it vanished off the radar.

Department of Civil Aviation director-general Datuk Azharuddin Abdul Rahman at a press conference Monday said samples from the oil spill have been collected from the scene and have been sent to the Chemistry Department for tests.

The Vietnam authorities on Saturday had reported of spotting two large oil spills but could not confirm if it came from the missing MH370 aircraft.

The marine engineer said he was offering his opinion on the matter to Astro AWANI as he did not want the effort to locate the missing aircraft be focused on the oil spill which may not have originated from an aircraft and did not want public confusion.

Meanwhile, an oil tanker captain with 31 years of experience in the field agreed with the marine engineer that the oil spills did not originate from aircraft.

“I have seen oil slicks like the like the one supposedly taken from a search aircraft many times. The yellow or cream nature of the slicks is characteristic of tank washings from an oil tanker,” he said.

“Aviation fuel is a non persistent fuel oil and leaves nothing more than a sheen on the surface of the water which, in sea temperatures in the area, would evaporate very quickly and certainly not leave a slick like those shown,” he said adding that it does not change colour as many believe.