By Marco Aquino

LIMA, July 2 (Reuters) - A protest by informal miners in Peru is blocking parts of a key copper corridor used by major miners MMG 1208.HK, Glencore GLEN.L and Hudbay HBM.TO, leaders of the action and an industry source said on Wednesday.

The demonstrators at the blockade in the Chumbivilcas province of the Cusco region are pushing Peru's government to extend a deadline to regularize informal mining operations, said Luis Huaman, one of the protest leaders.

The companies operating major copper mines in the area - MMG's Las Bambas, Hudbay's Constancia and Glencore's Antapaccay - did not immediately reply to requests for comment.

Reuters could not determine the scope of the potential impact to operations at the sites, which rank among the top 10 producers in the country, led by Las Bambas in the fourth slot.

The area is one of several nationwide where members of Peru's artisanal and informal miners organization, CONFEMIN, began staging protests on Friday.

"This blockade is in support of the national protest, for unconditional formalization," Huaman said in an interview. "We are not allowing (trucks from) large-scale mining to pass."

A mining industry source familiar with Las Bambas told Reuters that after several days of protest, the company is being affected, but did not provide further details.

Las Bambas has faced numerous protests in recent years, and has used longer alternate routes to avoid roadblocks.

(Reporting by Marco Aquino; Writing by Daina Beth Solomon; Editing by Paul Simao)

((daina.solomon@thomsonreuters.com;))