The statement gave no details of the injury or how it was inflicted, but it appealed to all Muslims to pray for the "speedy recovery" of Mr. Zarqawi, who has claimed responsibility for scores of suicide bombings, ambushes, drive-by assassinations and hostage killings, and attracted an American bounty of $25 million. Last week, a statement issued in his name on the same Web site justified the killing of Iraqi civilians in the course of insurgent attacks, saying it was "necessary if you must kill them to get at the enemy."
The Web posting, whose authenticity could not be confirmed, came as a series of insurgent attacks killed nine American troops across Iraq on Monday and Tuesday, bringing the three-day total of dead American servicemen to 14.
The attacks on Tuesday included a suicide car bombing on an expressway in southern Baghdad that killed three soldiers and reduced their Humvee to a tangle of charred scrap. The attacks continued a wave of insurgent violence that has killed 58 American troops and about 600 Iraqi civilians since the beginning of May.
The claim that Mr. Zarqawi was injured followed a series of unconfirmed reports that the Jordanian-born militant, named by Osama bin Laden as Al Qaeda's chief representative in Iraq, sought hospital treatment in the past month in at least two cities in the desert of western Iraq.
On Monday last week, Iraqi and American forces mounted a nighttime cordon around the Karkh Hospital in central Baghdad after a tip that Mr. Zarqawi had gone there for treatment, but they found no trace of him.
For weeks, American commanders in Iraq have said they believed they were closing in on Mr. Zarqawi, and they have cited the arrest of more than 20 of his "trusted lieutenants," including leaders of his terrorist cells, propaganda chiefs, bomb makers, drivers and others.
But an American general in Iraq who was reached by e-mail on Tuesday took a cautious view of the report that the militant leader had been injured, saying that while the American command did not discount the report, "we aren't banking on it, either."
"It could be a ruse to throw us off his trail," the officer said.
At the Pentagon, civilian and military officials said they had no evidence to either prove or disprove the report on Mr. Zarqawi.
Some who studied the Web posting said they believed it to be authentic. One of the first reports of the posting came from a Washington-based monitoring organization, the SITE Institute, which scrutinizes Internet postings by Islamic terrorist groups and offers subscribers English translations of the Arabic texts. Its director, Rita Katz, said in a telephone interview that the statement claiming Mr. Zarqawi had been injured appeared first on an Internet message board that has been used regularly for pronouncements by Mr. Zarqawi's group, Al Qaeda in Mesopotamia.
"I believe this is a very authentic message," Ms. Katz said. "I really believe this came from Al Qaeda in Iraq."
In a summary accompanying its translation, the SITE Institute described the statement as "a seeming elegy."
The statement, signed by Abu Maysara al-Iraqi, the Zarqawi organization's spokesman, described the militant leader's Islamic zeal as a "priceless thing" for the insurgents, and added: "Even the Prophet was injured. Let everybody know that the injury of our leader is an honor and causes us to surround our enemy tighter and is an encouragement for us to increase the intensity of attacks upon them."
Mr. Zarqawi, who is in his mid-30's, was first reported to be in Iraq during the last years of Saddam Hussein's rule, when Western intelligence reports said he had fled Jordan for refuge with an a Qaeda-linked Islamic group, Ansar ul-Islam, that operated in the mountains of Iraqi Kurdistan, along the Iranian border. After the American-led invasion two years ago, he became the leader, or sheik, of the Islamic militants, many of them from other Arab countries, who joined hard-line remnants of Mr. Hussein's government in mounting the insurgency.
The American command, and Mr. Zarqawi's own Web site pronouncements, have depicted him as a Pimpernel figure, moving undetected between the main centers of violence, in Baghdad, Falluja, Ramadi, Mosul and elsewhere. But since the American-led offensive that recaptured Falluja in November, which killed scores of Islamic militants and scattered others, American commanders have made the destruction of his network a priority, mounting operations they say have resulted in scores of his followers - in addition to 20 of his top lieutenants - being captured or killed.
Mr. Zarqawi has had several narrow escapes. Earlier this month, American officers confirmed that he had come close to being captured during an American raid along the Euphrates River north of Ramadi on Feb. 20. The commanders said a pickup carrying Mr. Zarqawi made an abrupt U-turn near an American checkpoint between the cities of Hit and Haditha, 100 miles east of the Syrian border, setting off a chase. The officers said Mr. Zarqawi leapt from the pickup and hid beneath an overpass, leaving his driver and another man to be captured, along with Mr. Zarqawi's laptop computer and more than $100,000 in cash.
Disclosure of the incident came as a 1,000-man Marine battle group mounted a weeklong offensive farther west along the Euphrates, seeking to disrupt or destroy parts of the Zarqawi network. On May 13, an Iraqi general was quoted in a report by the BBC's monitoring service as saying that Mr. Zarqawi had suffered critical head injuries during an American bombing raid on the border town of Qaim. The Iraqi officer was quoted as saying that Mr. Zarqawi had been treated for his injuries at a Ramadi hospital, but had left before Iraqi forces arrived.
Other reports appearing in Iraqi newspapers, also unconfirmed, have said Mr. Zarqawi was in a hospital in Haditha and went undetected when it was searched by American troops in early May. A report in The Sunday Times of London quoted an unidentified doctor in Ramadi as having said that "well-dressed" aides of Mr. Zarqawi's took him to a hospital there on May 11, four days after the Marine offensive began, and that he was "bleeding heavily" from unspecified wounds. The paper quoted the doctor as saying that he tried unsuccessfully to persuade Mr. Zarqawi to remain for treatment, only to be offered - and to have refused - "a wad of U.S. dollars to secure his silence."
The latest deaths among American troops included four soldiers from the 155th Brigade Combat Team who were killed Monday after a homemade bomb exploded near their convoy during what the American command described as "combat operations" in Haswa, south of Baghdad. Also on Monday, a Marine at a base in Ramadi was killed by what the military said was indirect fire, which normally means a rocket or mortar.
On Tuesday, three soldiers were killed in central Baghdad when their Humvee was struck by a suicide car bomb - the latest in a wave of similar attacks across Baghdad in recent weeks. The explosion occurred as an Army convoy neared an American base in the Rashid area of south Baghdad, an area of frequent insurgent attacks.
Half an hour later, a crewman in a Bradley armored vehicle that was serving as an observation post elsewhere in Baghdad was killed in a drive-by shooting, according to a command statement. There was more violence against Iraqi civilians on Tuesday, including a car bomb explosion near a school in Baghdad, killing at least two and wounding eight, the police said, though unconfirmed reports later in the day put the death toll at six. Reports from the scene suggested that none of the victims were students.