HELSINKI (AP) -- Standard and Poor's says it has downgraded Nokia's credit rating by one notch and warned that it may reduce it again unless it improves performance.

   Friday's downgrade comes after huge losses in the Finnish company's first quarter and a report that Samsung Electronics Co. has overtaken it as the world's largest maker of mobile phones.

   Last week, Nokia Corp. announced one of its worst quarterly results ever, blaming tough competition for a (euro) 929 million ($1.2 billion) net loss as sales plunged, especially in the smartphone market.

   Earlier, rival ratings agency Moody's dropped Nokia to near junk status in anticipation of the bad first-quarter results.