LIMA, June 30 (Reuters) - Peruvian copper producer Southern Copper, controlled by Grupo Mexico, plans on Monday to restart development of the long-postponed Tia Maria project, according to an internal document seen by Reuters.

The Tia Maria mine, in the Islay province of Peru's Arequipa region, has been on hold for years amid community opposition over fears of the mine's environmental impact. Protests against the mine left six people dead between 2011 and 2015. An internal memorandum issued by Grupo Mexico and Southern Copper on Friday and reviewed by Reuters notified employees about the start of work on Monday. A source with knowledge of the plans told Reuters that the document was authentic.

Grupo Mexico did not immediately respond to a Reuters request for comment.

In May, Southern Copper's vice president of finance, Raul Jacob, told Reuters that the $1.4 billion mine was slated to break ground by the end of the year or in the first half of 2025.

In 2019, the Peruvian government agreed with Southern Copper that development of the project could proceed when there were adequate social conditions. Jacob told Reuters in May that these conditions had improved.

The mine is eventually expected to produce 120,000 tons of copper annually.

Peru is struggling to accelerate its copper production, after Democratic Republic of Congo displaced it as the world's second largest copper producer in 2023. (Reporting by Marco Aquino in Lima, Peru; Editing by Mark Porter and Leslie Adler)