ArcelorMittal , the world's largest steelmaker, said on Thursday it had extended its credit lines by $1.2 billion until 2012, bringing the total amount of such refinancing to $6 billion.

The company said the operation affected debt maturing in 2010 and 2011.

ArcelorMittal said this forward start financing was structured by Calyon, the corporate and investment banking arm of Credit Agricole.

In February, the company said it had signed $4.8 billion of forward start agreements to extend some of its existing loans until 2012.

Forward starts are a popular way for companies to ensure access to liquidity. They allow borrowers to bypass the dysfunctional European syndicated loan market by locking in loans years ahead of maturity in return for increased fees and margins.

ArcelorMittal last month issued a 1.25 billion euro ($1.65 billion) convertible bond to diversify its sources of funding and also to lengthen its debt maturity profile.

The company, hit by a sharp downturn of auto and construction sectors affecting demand for steel, has a target of reducing debt by $10 billion by the end of this year.

It already achieved $6 billion of that in the fourth quarter of 2008, pulling its net debt down to $26.5 billion.

(Reporting by Philip Blenkinsop; Editing by Erica Billingham)