MEXICO CITY (Reuters) - North Korea's ambassador to Mexico on Friday said its tensions with the United States were not Mexico City's business after President Enrique Pena Nieto ordered that he leave the country in protest over Pyongyang's nuclear tests.

Mexico on Thursday said it had given the ambassador, Kim Hyong Gil, 72 hours to leave Mexico in order to express its "absolute rejection" of North Korea's recent nuclear activity, describing it as a grave threat to the region and the world.

The North Korean ambassador branded the move as "ignorant" and said disagreement over the country's nuclear program was an issue for the United States and "has nothing to do with Mexico."

"That is why I express great displeasure at the bilateral diplomatic measures taken by the Mexican government that claims to have a sovereign foreign policy. That (claim) is without basis," he told reporters outside the North Korean embassy in Mexico City.

Mexico has traditionally sought to steer clear of diplomatic spats, but in the past few months it has adopted robust language to condemn the governments of Venezuela and North Korea as they descended into increasing international isolation.

Mexico's foreign minister, Luis Videgaray, has led the diplomatic push as he also seeks to convince the United States to keep the North American Free Trade Agreement in place.

Mexico's move follows a tide of international condemnation of North Korea for repeated missile launches and the test of a powerful nuclear weapon in recent weeks.

Videgaray on Friday stressed that Mexico was not breaking diplomatic ties with North Korea, but that the country "wanted to send a clear message of absolute rejection" of the recent tests.

(Reporting by Roberto Ramirez; Editing by Leslie Adler)