Confirming months of bleak economic news, the European Union's head office slashed its growth forecasts for 2003 yesterday and said that even though things are slowly picking up, unemployment would probably worsen next year. The EC expressed general optimism about the future, but warned the long-term health of the European economy depended on gov-ernments following through on difficult welfare and labour market reforms. ''Our major challenge during the upturn will be to raise our growth potential,'' Pedro Solbes, EU economics com-missioner, said. ''We should not pass up this opportunity this time as we did in the last upturn in 1999-2000.'' In its biannual economic fore-cast, the commission pro-jected ''a mere 0.4%'' growth this year in the 12 countries using the euro, down from the already anaemic 1% estimated in April.