Tokyo - Japan's Nikkei 225 Stock Average extended losses in early trading Friday on prolonged economic concerns and the yen's strength against other currencies, with the benchmark index down 423.18 points, or 4.76 per cent, to 8,475.96.

The Nikkei lost more than 6 per cent in Thursday trading.

On currency markets at 9 am (0000 GMT), the dollar traded at 97.27-32 yen, down from Thursday's 5 pm quote of 97.90-93 yen.

The euro was quoted at 1.2690-95 dollars, down from Thursday's 5 pm quote of 1.2860-63 dollars, and at 123.42-52 yen, down from 125.92-96 yen. (dpa)