Chile's Codelco raised $2-billion in a bond offering in New York on Tuesday, as the world's top copper producer seeks to fund an investment drive to revive flagging output.

The company offered 10-year and 30-year notes. The 10-year was for $1.3-billion with a yield of 5.966%, or 210 basis points over the comparable US Treasury rate.

The 30-year, meanwhile, was for $700-million with a yield of 6.331%, or a spread of 195 basis points.

The state-run miner is not only battling to reignite copper production, which is at its lowest level in 25 years, but is also facing calls to rein in its debt, which has ballooned as costs have overrun at some of its key mines in the Andean country.

"This financing seeks to ensure the availability of resources for the development of a demanding portfolio of investments that for this year will need a total of $4.1-billion," Codelco said in a statement.

"This magnitude of capital is consistent with the higher level of activity of the structural projects, which are resuming their construction pace and which will help increase the firm's production level to 1.7 million (metric) tons in 2030."

Late last month, rating agency Moody's said it was reviewing a possible ratings downgrade for Codelco amid weakened production, rising costs and growing financial pressure. It said the firm would need to lift its investments to about $4-billion from $3.3-billion to boost its "structural projects."

Banks BNP Paribas, Citi, J.P. Morgan, Santander and Scotiabank are the joint bookrunners on the offer, IFR said.

Codelco's production slipped last year to about 1.45-million metric tons, the lowest in around a quarter of a century, and output has slipped further this year with the miner expecting to produce between 1.31-million to 1.35-million metric tons of copper.