US government figures show that the number of Americans filing new claims for jobless benefits fell more sharply than expected last week, extending a four-week decline. Claims for the week to September 11 fell to 450,000, down 3,000 from the previous week's revised figure, the Labor Department said. The latest figure was better than most economists' expectations of 460,000 new claims, sparking optimism about the recovery. Separate figures show that US producer prices rose slightly more than expected in August as energy prices recorded their first increase since March. The Labor Department said the seasonally adjusted index for prices paid at the farm and factory gate increased 0.4%, the largest increase in five months, after gaining 0.2% in July. Analysts had expected a 3% rise. In the 12 months to August, producer prices increased 3.1%, slowing from the previous month's 4.2% increase. Producer prices last month were bumped up by a 2.2% jump in energy costs. Petrol prices surged 7.5%, the largest increase since January, after falling 2.2% in July. Food prices fell 0.3%. Stripping out volatile food and energy costs, core producer prices edged up 0.1% last month, matching market expectations.