US military spokesman Lieutenant Colonel Barry Johnson said eight former high-value detainees, whom he declined to name, had been released.
"Many were originally held as suspects in possible war crimes and as material witnesses" in cases against the regime, he said.
"They no longer were deemed to have information in this regard," he said, adding that they were released Saturday.
An Iraqi lawyer said a total of 24 former senior Saddam officials had recently been released, including Huda Saleh Mahdi Amash, known as "Mrs Anthrax", and Rihab Taha, "Dr Germ".
"It was a decision taken on December 4," he said on condition of anonymity, adding that a number of them had received passports to leave the country.
Amash was ranked 53rd on the US-led coalition's list of most wanted officials and was arrested in May 2003 for her work in the regime's biologicial warfare program.
Taha holds a PhD in microbiology from a British university and was the director of an institute where scientists were carrying out research on anthrax and a bioterrorist agent based on botulism toxins.
The two were high ranking Baath party members and the only women in US hands.
Reports had been doing the rounds on Sunday about the release of several top figures from the old regime as part of a deal to appease the disaffected Sunni Arab minority in the aftermath of elections, a deal the lawyer confirmed.
Petrol protests
Meanwhile, thousands of angry Iraqis took to the streets to protest government-imposed gasoline (petrol) price increases and the oil minister threatened to resign if the measure was not reversed.
The public outcry follows price hikes of 300 percent introduced nationwide on Sunday, just three days after general elections for a new four-year term parliament.
In southern Iraq police fired in the air to disperse about 3,000 stone-throwing demonstrators in Nasiriyah who took to the streets to protest against the petrol price rise.
In a bid to restore calm, local officials ordered petrol stations to cancel the hikes.
In the southern town of Amarah, several dozen demonstrators threw stones at a British army patrol while chanting slogans hostile to Iraqi Prime Minister Ibrahim Jaafari.
Security forces dispersed demonstrators who surrounded petrol stations in Baquba, northeast of Baghdad, while further demonstrations took place in the northern city of Tikrit.
Oil Minister Ibrahim Bahr al-Ulum threatened to resign unless the government cancelled a decision to raise gasoline prices from 50 to 150 dinars equivalent to between three and 10 US cents.
"I call on the government to hold off on implementing this decision. One shouldn't punish Iraqis who risked their lives going to vote by increasing prices," he said.
Nearly half the government's budget currently goes to subsidizing goods and services, mostly in the energy sector.
Election results
Iraq’s electoral commission, citing initial partial results, said that in
Baghdad the Shiite-backed United Iraqi Alliance, currently in power, had won about 58 percent of the vote.
The Sunni-backed National Concord Front came second with 18.6 percent of the vote and the Iraqi National List led by former prime minister Iyad Allawi, a secular Shiite, third with 13.5 percent.
On Sunday, vice-president Adel Abdel Mahdi said the UIA was close to winning an absolute majority of seats.
Final results were not expected before the start of next year, the commission said.
Hostage video
A Sunni Arab extremist group has also issued a videotape on the Internet which showed the execution of a man described as an American contractor held hostage in Iraq.
The Islamic Army in Iraq had said in a statement on December 8 that it had killed Ronald Schultz, a security contractor.
The US State Department said it could not confirm his death.
Several other Western hostages, including at a Briton, a US and two Canadian aid workers, are still being held in Iraq.