CARACAS (REUTERS) - A strip of Venezuela's western coastline boasting pristine beaches and fragile ecosystems such as mangroves and coral reefs could take more than half a century to fully recover from the environmental impacts of a recent oil spill, a researcher said on Wednesday (Aug 19).

The country's opposition-controlled National Assembly last week opened an investigation to determine the causes and consequences of the oil slicks that began washing up on the Caribbean coast of western Falcon state in early August.

"We project that the negative consequences on ecosystems and their components could last for 50 years or more," biologist Julia Alvarez at Venezuela's SVE ecological society, told reporters.

Ms Alvarez added that the area was also home to mollusks that likely would have died instantly on contact with the oil, threatening the livelihood of fishermen in the area at a time of severe economic contraction in Venezuela.

Independent researchers and opposition lawmakers have said the spill likely originated from the El Palito oil refinery in nearby Carabobo state, citing satellite images showing slicks near the refinery in late July, days before oil began washing up on the coasts of Morrocoy national park.

A report published by the SVE and Venezuela's Simon Bolivar University cited satellite images showing that the slick first appeared on July 22 near the refinery. Given its length of 5.6km and width of 1.5km, the researchers calculated it contained around 26,700 barrels of oil.

Venezuela's environment ministry, known as the Ministry of Ecosocialism, has said it has managed to contain the spill and is working to clean up the affected area. But authorities have not commented on the spill's cause, nor on the quantity or type of hydrocarbon leaked.