The United States is asking Mexico to review whether the labor rights of pilots at a small cargo airline are being infringed, the eight such request Washington has made this year, U.S. officials said on Wednesday.

Since the U.S.-Mexico-Canada Agreement (USMCA) on trade took effect in 2020, the office of the U.S. Trade Representative has now launched a total of 13 labor rights complaints against facilities in Mexico.

The United States wants Mexico to probe if pilots at Mas Air, a Mexico City-based cargo airline, are being denied the right to freedom of association and collective bargaining. The carrier's web page says it operates five planes.

"Today's action highlights the United States is committed to safeguarding the labor rights enshrined in the USMCA across industries and sectors," Trade Representative Katherine Tai said in a statement.

Washington wants the Mexican government to review the matter under the USMCA's Rapid Response Labor Mechanism. Mexico has 10 days to agree to conduct a review and, if it agrees, 45 days from Wednesday to complete the review.

(Reporting by David Ljunggren; Editing by Sandra Maler)