SANTIAGO, Nov 28 (Reuters) - Chile's state-owned miner

Codelco, the world's largest copper producer, said on

Thursday it had reached a new collective bargaining agreement

with the union in charge of developing some of its most

important mines.

The new 36-month agreement with the workers from company's

projects unit affects some 620 employees and will come into

effect on Dec. 1, Codelco said, without providing financial

details of the new deal.

The unit runs the development of Codelco's major projects

designed to extend the life of its key mines, compensate for a

drop in ore grades and boost production levels.