Fitch Ratings upgraded long-term issuer default rating of Aluminum Corp. of China (HKG:2600, SHA:601600), also known as Chalco, to A- from BBB+, citing the upgrade of its parent, Aluminum Corporation of China (Chinalco), and strong operational and strategic ties between the two.

The rating outlook is stable.

Fitch said Chalco's ratings are equalized with Chinalco's under its parent-subsidiary linkage criteria, reflecting Chinalco's strong incentive to support the company. Chinalco, which owns about 32% of Chalco, is rated A- with a stable outlook and sits one notch below China's sovereign rating due to its strategic role and high likelihood of state support.

The ratings agency said Chalco is Chinalco's main operating platform for its aluminium and alumina businesses, contributing about half of the parent's revenue and EBITDA while supplying most of its aluminium fabrication needs.

Fitch said the ratings could come under pressure if China's sovereign rating is downgraded, state support for Chinalco weakens, or ties between Chinalco and Chalco diminish. An upgrade would likely require a higher sovereign rating or stronger state support for Chinalco.