The spill in Ecuador's northwest on Thursday was believed to have been caused when a landslide ruptured a major pipeline, releasing tens of thousands of barrels of oil.

The crude has since spread to at least five waterways, including the Esmeraldas River that flows into the Pacific Ocean.

State-owned Petroecuador, which manages the damaged pipeline, announced Tuesday it was suspending exports of the Oriente crude -- one of two varieties that the South American country produces -- due to the force majeure clause.

The company hopes that invoking the clause will shield it from penalties and potential breaches of contract from clients.

The "emergency declaration will not last longer than 60 days and aims to... allocate all necessary resources to minimize the impact of the force majeure event on hydrocarbon exploration, exploitation, transportation, and marketing operations," Petroecuador said in a statement.

About half a million people have been affected in one way or another, many cut off from potable water in a region heavily reliant on rivers for this commodity, Esmeraldas mayor Vicko Villacis told the Teleamazonas network Tuesday.

He estimated the amount of oil spilled at approximately 200,000 barrels.

Petroecuador, which has not quantified the amount spilled, was using tanker trucks to recover as much as possible of the spilled crude from areas where many people make a subsistence living of fishing.

Three ships are expected to bring drinking water to Esmeraldas starting Tuesday, the company said.

The government has also declared an environmental emergency in the province, home to a wildlife refuge with more than 250 animal species.

- Dependence on the rivers -

Ecuador produced about 475,000 barrels of oil per day in 2024 -- one of its main export products.

The burst pipeline is part of the Trans-Ecuadorian Pipeline System, which can transport 360,000 barrels per day on the 500-kilometer (310-mile) journey from the Amazon to the Pacific coast.

"There are no life forms in the water" of two affected rivers where "a mixture of oil and water circulate," marine biologist Eduardo Rebolledo of the Catholic University of Esmeraldas told a local TV channel.

"In rural Esmeraldas, drinking water is limited, people depend heavily on the rivers, and people use the river water," he said.

In Rocafuerte, a fishing village in Esmeraldas, AFP saw several boats and their nets covered in black oil.

"If it continues like this, we won't be able to fish anymore," resident Luis Cabezas said.