The spill in the country's northwest last 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 from the Esmeraldas River, where it started, to at least four other waterways.

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.

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

State-owned Petroecuador, which manages the damaged pipeline, 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.

It has not quantified the amount spilled, but Villacis estimated it was about 200,000 barrels.

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

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

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

In Rocafuerte, a fishing village in Esmeraldas, AFP observed 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 told AFP.