SANTIAGO, Sept 5 (Reuters) - Chilean state-run miner

Codelco has purchased Enami's 10% stake in Teck's Quebrada

Blanca mine in northern Chile for $520 million, it said on

Thursday.

The deal will contribute 25,000 to 30,000 tons of copper

to Codelco's annual output, the company said, at a time when the

the world's top copper miner is struggling to boost declining

production levels.

Codelco said it will maintain the share rights held by

Enami, which is also a state-run mining company. Those include

preferential dividends, protection from dilution in future

capital increases and the ability to appoint two of 11 board

members.

Codelco Chairman Maximo Pacheco in a statement said the

deal highlights the company's efforts to ensure "enhanced access

to large-scale assets, reduced risk and diversified

opportunities."

Teck did not immediately respond to a request for

comment.

Enami last year valued its stake in Quebrada Blanca at

$323.8 million. In a statement about the sale to Codelco, it

said the deal will help reduce Enami's debt to $250 million from

$740 million.