The American military has not properly tracked hundreds of thousands of weapons intended for Iraqi security forces and has failed to provide spare parts, maintenance personnel or even repair manuals for most of the weapons given to the Iraqis, a federal report released Sunday has concluded.

The report was undertaken at the request of Senator John W. Warner, the Virginia Republican who is the chairman of the Senate Armed Services Committee and who recently expressed an assessment far darker than the Bush administration's on the situation in Iraq.

Mr. Warner sent his request in May to a federal oversight agency, the Special Inspector General for Iraq Reconstruction. He also asked the inspector general to examine whether Iraqi security forces were developing a logistics operation capable of sustaining the hundreds of thousands of troops and police officers the American military says it has trained.

The answers came Sunday from the inspector general's office, which found major discrepancies in American military records on where thousands of 9-millimeter pistols and hundreds of assault rifles and other weapons have ended up. The American military did not even take the elementary step of recording the serial numbers of nearly half a million weapons provided to Iraqis, the inspector general found, making it impossible to track or identify any that might be in the wrong hands.

Exactly where untracked weapons could end up — and whether some have been used against American soldiers — were not examined in the report, although black-market arms dealers thrive on the streets of Baghdad, and official Iraq Army and police uniforms can easily be purchased as well, presumably because government shipments are intercepted or otherwise corrupted.

In a written response to the inspector general's findings, the American military largely conceded the shortcomings. The military said it would assist the Iraqis in determining the spare parts and maintenance requirements for the weapons. The military also said it has now instituted a "process to accurately issue weapons by quantity and serial number listing."

Because the inspector general is charged only with looking at weaponry financed directly by the American taxpayer, the total of lost weapons could end up being higher. The Government Accountability Office and the Pentagon inspector general are expected to look at weapons financed by all sources, including the Iraqi government.

The inspector general's office, led by Stuart W. Bowen Jr., also a Republican, responded to Mr. Warner's query about the Iraqi Army's logistical capabilities with another report released at the same time, concluding that Iraqi security forces still depended heavily on the Americans for the operations that sustain a modern army: deliveries of fuel and ammunition, troop transport, health care and maintenance.

Mr. Bowen found that the American military was not able to say how many Iraqi logistics personnel it had trained — in this case because, the military told the inspector general, a computer network crash erased records. Those problems have occurred even though the United States has spent $133 million on the weapons program and $666 million on Iraqi logistics capabilities.

The report said that although the United States planned to scale back its support for logistics and maintenance for Iraqi security forces in 2007, it was unclear whether the Iraqi government had any intention of compensating by allocating sufficient money to the Ministries of Interior and Defense.

Mr. Warner confirmed through his spokesman, John Ullyot, that he was reviewing the reports over the weekend in advance of a scheduled meeting with Mr. Bowen on Tuesday.

Mr. Warner "believes it is essential that Congress and the American people continue to be kept informed by the inspector general on the equipping and logistical capabilities of the Iraqi Army and security forces, since these represent an important component of overall readiness," Mr. Ullyot said.

Mr. Bowen said in an interview that he was particularly concerned about whether the Iraqi government intended to allocate enough money to support the logistics and maintenance needed for the Iraqi security forces to operate effectively.

"There's a couple of red flags," Mr. Bowen said. "Most significantly, is the Iraqi Ministry of Interior properly preparing to take over the mission and sustain it?"

"We don't know because we don't have adequate visibility into their budgeting," he said, "and to a lesser extent the same red flag is up for the Department of Defense."

Another report unrelated to Mr. Warner's request was also released by the inspector general on Sunday, on the so-called provincial reconstruction teams that the United States is creating for the next phase of rebuilding Iraq's infrastructure.

 While some of the teams, intended to be scattered in each of Iraq's 18 provinces, are functioning, security problems have severely hampered work in others, the report says. As a result, the inspector general recommended, the United States should consider reassigning its personnel in six provinces — including Basra in the south and Anbar in the west — to other places where effective work can be done.

The western province of Anbar is a central focus of the Sunni insurgency, and power struggles between Shiite militias have made Basra increasingly violent. The other four provinces that the inspector general recommends essentially abandoning are also in the Shiite south.

In its assessment of Iraqi weaponry, the inspector general concluded that of the 505,093 weapons that have been given to the Ministries of Interior and Defense over the last several years, serial numbers for only 12,128 were properly recorded. The weapons include rocket-propelled grenade launchers, assault rifles, machine guns, shotguns, semiautomatic pistols and sniper rifles.

Of those weapons, 370,000 were purchased with American taxpayer money under what is called the Iraq Relief and Reconstruction Fund, or I.R.R.F., and therefore fell within the inspector general's mandate.

Despite the potential risks from losing track of those weapons — involving 19 different contracts and 142 delivery orders — the United States recorded serial numbers for no more than a few thousand, the inspector general said.

There are standard regulations for registering military weaponry in that way, governed by the Department of Defense small-arms serialization program. The inspector general's report said that when asked why so many weapons went to Iraq with no record of serial numbers, American military officials in Baghdad replied that they did not believe the regulations applied to them.

Still, in their response to the report, military officials said they would keep track of serial numbers for weapons shipped or issued in the future, but in a database outside the small-arms serialization program. They did not present a plan for identifying or monitoring weapons that had already been issued.

The inspector general's report also found that money for spare parts was allocated for only 5 of the 12 different kinds of weapons sent to Iraq — and when the inspector general contacted units of the Defense and Interior Ministries, none actually knew how or where to requisition spare parts.

There were also significant discrepancies in the numbers of weapons purchased and those in Iraqi warehouses. While 176,866 semiautomatic pistols were purchased with American money, just 163,386 showed up in warehouses — meaning that more than 13,000 were unaccounted for. All 751 of the M1-F assault rifles sent to Iraq were missing, and nearly 100 MP-5 machine guns.

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