Steelmaker POSCO has had its credit rating downgraded by one notch from A- to BBB+ by credit ratings firm Standard & Poor's.

The decision is due to sluggish demand for steel amid the prolonged global downturn and follows similar downgrades for other top steel manufacturers.

In October last year, S&P lowered POSCO's credit rating from A to A-, citing weakened profitability due to plummeting global demand. The following month, Moody's also adjusted POSCO's outlook from positive to negative.