"The drop in awareness comes as press attention to the war has waned," the report said.
A scant three percent of news stories in February were devoted to the Iraq war, compared with around 15 percent in July last year, and the US public has not perceived the war, which began nearly five years ago, as a top news story since October, the report noted.
Meanwhile, 28 percent of 1,003 adults polled last month for Pew correctly estimated the number of US military fatalities in Iraq at around 4,000, compared with 54 percent who got the figure right seven months ago, the report said.
More than one-third -- 35 percent -- estimated that 3,000 had been killed, 11 percent put the toll at 2,000 deaths, and just under a quarter said the number of fatalities was closer to 5,000.
The Department of Defense confirmed the deaths of 3,974 US military personnel in Iraq as of Monday, according to Pew.
"As news coverage of the war has diminished, so too has public interest in news about Iraq," the report said.
And with the waning interest in news about Iraq, there has been a "significant increase in the number of Americans who believe that military progress is being made in Iraq," it said, citing another poll.
That poll, which surveyed 1,508 adults between February 20-24, showed that nearly half of Americans -- 48 percent -- felt the US military effort in Iraq was going well, compared with 30 percent who thought so in February 2007, when the war was consistently one of the top news stories in the United States.
"Iraq was the public's most closely followed news story in all but five weeks during the first half of 2007," but lost power after July and fell out of the top stories in mid-October, the report said.
© 2008 Agence France Presse