SANTIAGO (Reuters) - An extended delay in enacting reforms in Chile aimed at expediting mining permits represents a "serious" problem for the industry in the world's top copper-producing country, the local head of U.S. miner Freeport-McMoRan said on Tuesday.

Chile, also the world's second-biggest producer of the key battery metal lithium, is grappling with regulatory hurdles that miners also argue slow project development.

President Gabriel Boric's government is pushing for reforms to streamline mining permits in addition to modifying environmental assessments. The reforms are currently under discussion by lawmakers.

"The issue of permits is a serious one," said Mario Larenas, Freeport's top executive for Chile, at a seminar organized by EY and Cesco in Santiago.

He described the legislation as "perfectible" and "on the right track," but lamented the delay in the legislative process.

"Initially, when they were presented, the idea was to have them ready by the end of the year and that won't happen."

Freeport is a major gold and base metals producer, especially copper and molybdenum, operating projects in the United States, Peru, Chile and Indonesia.

The company plans to invest $7.5 billion to expand its open-pit El Abra copper mine by 2025, pending an environmental permit.

The project's minority partner is Chile's state-run copper company Codelco.