WASHINGTON, June 13 — As the war in Iraq continues for a fourth year, the global image of America has slipped further, even among people in some countries closely allied with the United States, a new opinion poll has found.

Favorable views of the United States dropped sharply over the past year in Spain, where only 23 percent said they had a positive opinion, down from 41 percent last year, according to the survey. It was done in 15 nations, including the United States, this spring by the Washington-based Pew Research Center.

Other countries where positive views dropped significantly include India (56 percent, down from 71 percent); Russia (43 percent, down from 52 percent); and Indonesia (30 percent, down from 38 percent). In Turkey, only 12 percent said they held a favorable opinion, down from 23 percent last year.

Declines were less steep in France, Germany and Jordan, while people in China and Pakistan had a slightly more favorable image of the United States this year than last. In Britain, Washington's closest ally in the Iraq war, positive views of America have remained in the mid-50-percent range in the past two years, down sharply from 75 percent in 2002, before the war.