Security forces in Iraq have been placed on alert on the first anniversary of the execution of former President Saddam Hussein.
Saddam was taunted as he was being executed
His supporters are expected to gather at his power base in the city of Tikrit, and at his grave nearby.
Saddam was hanged after being convicted of the killings of nearly 150 Shia Muslims in Dujail in the 1980s.
He was taunted by his executioners shortly before his death, conduct which embarrassed the Iraqi government.
Scenes from the execution were captured on mobile telephones and quickly distributed around the world, prompting US President George W Bush, among others, to criticise the way the death sentence was carried out.
The killing of the 69-year-old Sunni leader worsened the rift with Shia groups in Iraq.
Iraqi officials conceded that some supporters would visit the grave where Saddam is buried next to his sons Uday and Qusay, who died in a gun battle with US forces in 2003.
"There are men who used to support him, and there are still some of his loyalists left," said interior ministry spokesman Abdul Karim Khalaf.
"If we see any criminal acts aimed at harming our fellow citizens, there are preparations and procedures in place to make certain that such attempts fail," he added.
On Saturday, about 2,000 people commemorated the former Iraqi leader at a rally in the Jordanian capital, Amman.
Iraqi government officials maintain that Saddam's execution ended all hope among his supporters that he might return to power, says the BBC's Humphrey Hawksley in Baghdad.
The authorities say it contributed to the shift of loyalty of many Sunnis away from the insurgency towards the mainstream political process.
Other members of Saddam's government are still awaiting execution including former Defence Minister Sultan Hashim al-Tai and senior army chief Hussein Rashid al-Takriti.
Ali Hassan al-Majid, better known as "Chemical Ali", is also on death row, after being convicted of ordering gas attacks in Kurdish areas of the country in 1988.