Chevron has been ordered to pay more than $19 billion in environmental damages, $1 billion more than originally decided, after an Ecuadoran court adjusted the amount on appeal, a source said.

"Due to an involuntary calculation error, the reparations now amount to $19,021,552,000," said a court source in the northeastern Amazonian province of Sucumbios.

Some 30,000 indigenous people and local farmers say the US oil firm Texaco contaminated large areas of Ecuador's Amazon Jungle when it operated in the region from 1964 to 1990, roughly a decade before Chevron acquired the company.

After years of litigation, an Ecuadoran court in February 2011 ordered the company to pay $18 billion in damages.