U.S. and Mexican officials on Tuesday said 13,000 Mexican migrant workers are owed a total of $6.5 million in unpaid wages from U.S. workplaces, and will work to help beneficiaries now living in Mexico claim their pay from U.S. labor authorities.

U.S. Ambassador to Mexico Ken Salazar said the effort marked an unprecedented collaboration between the U.S. and Mexico to support workers who for years have been short-changed.

“In past governments, this would not have happened,” he said at an event in Mexico City alongside Mexican labor officials.

“Now, because of the relationship we have … workers who have paid with their sweat will receive the pay they deserve.”

The U.S. Department of Labor’s Wage and Hour Division, which enforces labor law and recovers unpaid wages, determined who was owed back-wages through its inspections of U.S. workplaces, Mexico’s Labor Ministry said in a statement.

It will share a list of names with Mexican officials so they can attempt to locate the workers – many of whom had not been paid the legal minimum, or had not been paid for overtime.

Officials did not detail the industries or companies that had hired the workers, or the period for which they were owed.

Thea Lee, deputy undersecretary for international affairs at the U.S. Labor Department, said the effort to help Mexican workers was a pilot program that showed the U.S. commitment to workers in the country regardless of their migration status.

“They deserve protection under our laws,” she said in a video transmission at the event.

Mexico will also launch a public campaign to encourage workers to come forward if they believe they qualify for checks.

“The work ahead is to find these 13,000,” Mexican Labor Minister Luisa Alcalde said.