Officials at state-owned miner Centromin said that they planned to auction Cobriza July 6 with a minimum bid price of $7.5 million. They declined to give a reason for the postponement. Cobriza, located in the Andes with 51,000 hectares of mining concessions, has proven and probable reserves of almost 16 million tonnes graded at 1.24 percent copper and 16 grams of silver per tonne.

Centromin, which has privatised most of it major assets since 1992, has made no important sell-offs this year as potential buyers -- hit by low metal prices -- have trimmed investment plans due to cash-flow worries.

As part of its $700 million target for all privatisation revenue this year, the government officially predicts the treasury will receive about $300 million from mining sector sales.

But after severalauction postponements -- including that of its large copper deposit, Michiquillay -- local macroeconomic analysts are sceptical Peru can reach its 1998 mine sales target. Since the government began its widespread privatisation programme in 1991, it has raised almost $8 billion.