JAKARTA, March 28 (Reuters) - Copper miner Freeport

Indonesia has warned the Indonesian government that banning

exports of copper concentrate in June could lead to a loss of $2

billion in revenues for Jakarta, a company official said on

Thursday.

Indonesia's export ban takes effect from June in an effort

to force miners to invest in domestic smelting facilities, thus

adding value to their products, boosting earnings from exports.

Freeport Indonesia, controlled by mining giant Freeport

McMoran ( FCX ), though the Indonesian government is a majority

shareholder, has called for the ban to be relaxed as its Gresik

smelter would not be operating at full capacity by June.

"If we can't export, state revenues will drop by around $2

billion, based on current prices," media quoted Chief Executive

Tony Wenas as saying in remarks confirmed by a company

spokesperson.

The comments followed a meeting with President Joko Widodo,

at which he was accompanied by Freeport McMoran's ( FCX ) chairman

Richard Adkerson and incoming chief executive Kathleen L. Quirk.

Wenas reiterated that construction of the Gresik smelter

would be complete by May and start operating the following

month, reaching full capacity later in 2024.

A spokesperson for Indonesia's mining ministry declined to

comment. The president's office did not immediately respond to a

Reuters' request for comment.

Wenas has previously said Freeport Indonesia would have to

cut ore production by 40% this year if the government did not

delay the ban.

On Wednesday, Indonesian copper miner Amman Mineral

Internasional said it was also negotiating with the government

to relax the ban since its smelter would not be ready by May,

arguing that the government earns tax revenues from Amman as

well as Freeport.

Freeport also raised the matter of extending its mining

permit during the meeting, Wenas said.

Widodo and Adkerson met last November to discuss a 10%

increase in Indonesia's ownership of Freeport Indonesia and a

20-year extension of its mining permit beyond the current expiry

date of 2041.