UPDATE 1-Vulcan mining unit shut down by Mexican authorities, company says

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MEXICO CITY, May 5 (Reuters) - Mexican officials on Thursday ordered a halt to limestone quarrying at a Vulcan Materials Co. unit in the coastal state of Quintana Roo, the company said, days after Mexico's president promised to take legal action against the firm.

U.S.-based Vulcan, which said it had operated in Mexico for more than 30 years, called the shutdown orders "unexpected" and said it believed the government's action was illegal.

Mexican President Andres Manuel Lopez Obrador has previously criticized Vulcan's "destruction" of the area, saying Monday he would take legal action to stop its mining in the area.

"It will proceed legally, because there is a violation of the laws," he said at a regular press conference.

A spokesperson for Lopez Obrador did not immediately respond to a request for comment.

Vulcan, a leading producer of gravel, sand and crushed stone, said government officials arrived at the site of its Mexican subsidiary Sac-Tun with orders to stop underwater quarrying and extraction.

The company said in a statement it had legal permits to mine on the land, which it owns, and that it intends to "vigorously pursue all lawful avenues available" to resume operations.

Its Sac-Tun subsidiary, previously known as Calica, has several concessions in the southeastern state of Quintana Roo, where it mines crushed limestone that is later shipped to the United States, where it is used in construction.

The Mexican government said in February it was negotiating the settlement of a $1.1 billion lawsuit by Vulcan over the closure of a mine near the resort town of Playa del Carmen, and that it had proposed to turn the area into a tourist zone.

Mexican Interior Minister Adan Augusto Lopez said last month the company had agreed to the proposal. (Reporting by Kylie Madry; editing by Richard Pullin)