The claim by PacRim Cayman LLC is part of arbitration hearing over a failure by the government to issue necessary mining licences for the company's El Dorado gold project.
Pacific Rim said Monday that the arbitration is in its final, merit-based phase before the World Bank's International Centre for Settlement of Investment Disputes.
The tribunal will determine whether El Salvador broke its investment laws by refusing to issue the necessary mining licences for the project.
It will also determine El Salvador's monetary liability for the any breach of the investment protections for foreigners under those laws.
The company said the design for the El Dorado mine was submitted to Salvadoran authorities eight years ago and "exceeds current Canadian and U.S. environmental standards."
"Had El Salvador followed its own laws, the El Dorado mine would be in operation today, employing thousands of Salvadorans in one of the poorest regions of the country," the company said, adding that the project would be the single biggest taxpayer in El Salvador.