The Mexican defense ministry has alerted Washington about inflows of arms that are supposed to be "for the exclusive use of the US army," Foreign Minister Alicia Barcena said at a news conference.

"It's very urgent that an investigation be carried out," she added, without give more details.

The arms smuggling was one of the issues discussed by the two countries in Washington on Friday during a visit by Barcena and other senior Mexican officials, she said.