Mexico City, March 8 (RHC-Xinhua) -- Mexico is "gravely concerned" over a U.S. proposal to separate undocumented migrant families crossing the U.S.-Mexico border, Foreign Minister Luis Videgaray said on Tuesday.

"Mexico's position was expressed clearly and in a timely manner," and "we hope the opinion of the Mexican government has an influence on the decision the U.S. government finally takes," said Videgaray.

Last week, the U.S. State Department said it was mulling a policy to separate families as a way to discourage the arrival of undocumented migrants. The scheme would place children in protective custody while their mothers are sent to detention centers to await deportation.