The new report shows that there are far more companies to track than previously known, with backgrounds that are far more varied than earlier disclosures had suggested. And research by the federal investigators indicates that more than five years into the conflict, there is still no central database to account for all the security companies in Iraq financed by American money.

The investigators pieced together information from individual rosters at the Pentagon, the State Department and the United States Agency for International Development, as well as several independent federal databases that track procurement and contractors. The agencies alerted investigators that none of their repositories of information were believed to be 100 percent accurate.

Indeed, the Pentagon disputed some of the inspector general’s findings, saying it could confirm only 77 of the entries, involving about $5.3 billion in contracts. But by using the overlapping if incomplete databases, the investigators say they have determined that at least another 233 companies shared $662 million in additional work for guards, escorts and possibly less dangerous work like computer security.

Because all of the databases are incomplete, estimates of the number of security companies and the money spent on their contracts are likely to grow, the report indicates.

None of the handful of companies contacted by The Times denied having received security contracts in Iraq.

David Westrate, a senior vice president at MVM Inc., an American security company ranked 16th in terms of the amount of money it had been paid to provide security in Iraq  about $38 million on 21 separate Pentagon contracts  said, “We cannot confirm the numbers as you’ve given them to us, but I’m not surprised that we’re in the top 20.”

Perhaps the most eye-opening aspect of the list is the variety in the types of companies listed. Agility Logistics, formerly called Public Warehousing Company, is widely known as a colossus in the business of delivering food and other supplies to troops in Iraq.