WARSAW, Poland (AP) _ The government devalued the Polish currency, the zloty, by 15.6 percent Saturday against the dollar and other Western currencies, the official Polish news agency PAP reported.

It said the new official exchange rate will be 170 zlotys per dollar compared to the old rate of 147.

The zloty has declined in value more than 500 percent since 1980. On the black market, a dollar can buy up to 650 zlotys.

Government spokesman Jerzy Urban had told a news conference Tuesday the zloty would be devalued in an effort ''to promote Poland's exports'' and improve the country's foreign trade.

Poland needs to boost exports to meet payments on its $29 billion foreign debt and import vital supplies from the West that are needed to increase industrial production.