The government announced the arrest of Zarqawi lieutenant Sami Mohammad Said al-Jaf, also known as Abu Omar al-Kurdi, blamed for a string of deadly strikes in the country.

Iraqi authorities say Kurdi was responsible for 32 attacks, including the devastating 2003 bombing of the Baghdad UN headquarters that killed 22 people, including UN envoy in Iraq, Sergio Vieira de Mello.

He is also believed to be behind the assassination of Shiite leader Ayatollah Mohammed Baqr al-Hakim and the truck bombing of the Jordan embassy.

Zarqawi’s propaganda mastermind, Hassan al-Dulaimi, who confessed Kurdi had been plotting attacks on polling centres to disrupt Sunday’s vote, was also arrested.

An audiotape message on the internet purportedly from Zarqawi – who has a 25-million-dollar price on his head – emerged on Monday in which he declared all-out war on the elections and singled out the country’s Shiite majority.

His network claimed responsibility for a suicide car bomb attack on Monday at a checkpoint near Prime Minister Iyad Allawi’s party headquarters in Baghdad that left two dead and 10 wounded.

Meanwhile, the methods employed by Iraqi forces in battling the insurgency came under new scrutiny as a senior US official admitted the security apparatus was guilty of human rights abuses.

“Their record is not spotless on human rights,” the official said, adding the US embassy had registered its concerns with the Iraqi government.

In northern Iraq, Arab candidates running in Kirkuk’s provincial election have pulled out of the race in protest at the government’s decision to grant displaced Kurds the right to vote, the head of the Arab electoral list said.

Despite the set backs, Prime Minister Allawi remained upbeat and predicted Iraqis would turn out en masse to vote in the country’s first multi-party elections in half a century and the first since Saddam fell in April 2003.