Jungle residents have waged a decades-long battle over the responsibility of Chevron, which acquired Texaco, with pollution associated with oil waste pits in a remote part of Ecuador.

Plaintiffs obtained a $19 billion judgement in their favor last year, and sought to enforce the ruling in other countries including Argentina as Chevron has no substantial assets in Ecuador at present.

That has made for an awkward situation for ongoing talks between the US supermajor and YPF, which is entering the end of a four-month negotiation period for a potentially multibillion shale deal following the signing of a memorandum of understanding last December.

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