An appeals court in Ecuador upheld an $18 billion ruling against Chevron Corp. on Tuesday for oil pollution in the Amazon rain forest more than two decades ago.

The ruling confirmed a February judgment in the case. The Ecuadorean plaintiffs said in a statement that the decision is based on scientific evidence presented at trial proving that waste had poisoned the water supply.

"The appellate court relied on a record that proved that Chevron has violated the rights of the communities where it operates," the plaintiffs said in the emailed statement.

The lawsuit deals with pollution of the rain forest by energy company Texaco, which Chevron bought in 2001.

Chevron denounced the appeals court's decision and said it will continue to seek recourse in other courts outside Ecuador.

"Today's decision is another glaring example of the politicization and corruption of Ecuador's judiciary that has plagued this fraudulent case from the start," Chevron said in a statement.

The San Ramon, California-based company has previously alleged fraud in the lawsuit. The plaintiffs have also accused Chevron of defrauding the Ecuadorean court to hide the scale of the oil contamination.