The Republic of Ecuador has sued the Chevron Corp. as the two battle over liability for pollution in the Amazon rainforest.
The suit was filed Thursday in U.S. District Court in Manhattan.
Ecuador is asking the court to block an attempt by Chevron to force their dispute over the environmental damage into international arbitration.
Separately, Chevron is defending itself against a $27 billion lawsuit in Ecuador brought by 30,000 inhabitants of a rainforest where illnesses have been blamed on contamination from oil drilling.
Chevron says Ecuador, not the company, should have to pay any damages.
In a written statement, Chevron spokesman Kent Robertson said the government of Ecuador had long sought to evade its contractual obligations to Chevron.
"With today's filing, the government of Ecuador is simply seeking to delay the arbitration and avoid ever having to own up for its abrogation of the rule of law and violation of its treaty obligations to the United States," Robertson said.