SAMARRA, Dec 28: At least 42 people were killed in a string of attacks on Iraqi security forces and other targets on Tuesday after Osama bin Laden declared Jordanian radical Abu Musab al Zarqawi his "amir" in the country.

In an audio tape purportedly recorded by the Al Qaeda leader, Osama bin Laden also said all those who took part in the Jan 30 elections would be "infidels", raising the stakes in the run-up to the vote.

In one of a series of apparently coordinated strikes in Sunni strongholds north of Baghdad, guerrillas stormed a police station in Dijla, between Tikrit and Samarra, and gunned down 12 policemen.

"Armed men took control of the police station and executed 12 policemen, three of them officers," one police source said, adding that the attackers then dynamited the building.

Just outside Tikrit, the hometown of former president Saddam Hussein, three policemen were killed in an attack on a checkpoint. Another four policemen and a national guardsman were shot dead at a police station in Ishaki, south of the restive town of Samarra.

Three guardsmen and three civilians were killed in a car bomb attack targeting a US-Iraq military convoy in Samarra, hospital sources said. The US military confirmed a car bombing near a tank, but said it had no record of the deaths and that there were no US casualties.

In Baquba, 50 kilometres northeast of the capital, six national guardsmen were killed in a suicide car bomb attack. At Al Shurqat, 180 kilometres north of Samarra, two policemen were killed in an attack on their post, an official said.

In the same area, an Iraqi intepreter for the US army was killed and an Iraqi businessman travelling with him was kidnapped, another official said. A roadside bomb killed one Iraqi civilian and wounded another on a road frequented by US convoys near Baiji, 200 kilometres north of Baghdad, a hospital official said.

Three Iraqi businessmen working with the US army were killed at Suleyman Beg, 155 kilometres north of Baghdad, and a curfew imposed on the city afterwards. In Baghdad, a suicide bomber was killed and six people wounded in an attack against the convoy of an Iraqi national guard general Modher Abud as he was leaving his home, the interior ministry said.

Another policeman was killed in Balad when guerrillas opened fire on security forces guarding a voter registration centre. The latest bloodshed brought to at least 74 the number of people killed in attacks throughout the country since Sunday evening, including two US soldiers.

Iraq's nascent security forces have been crippled by a relentless and vicious campaign by guerillas, casting doubt on whether they would be able to handle securing next month's crucial elections without massive help from US-led troops.

Highlighting the perils in Iraq before the first post-Saddam vote, a voice recording attributed to Osama bin Laden and aired on Al Jazeera television on Monday warned all those who participate in the vote would be "infidels".

The voice also anointed Zarqawi, Iraq's most wanted man who is blamed for some of the worst bombings, assassinations and beheadings, as Osama's representative in Iraq.

"The brother mujahid Abu Musab al Zarqawi is the amir of the Al Qaeda Organization in the Land of Two Rivers," said the message, whose authenticity could not be confirmed.

"Brothers in the group must listen to him and obey him for what is good." Zarqawi, who has a 25 million dollar price on his head, has previously professed his animosity and hatred towards Iraq's Shia community calling it "the fifth column of Islam".

In the latest attack against Shias and their leaders, a car bomb exploded on Monday outside the headquarters of Abdel Aziz al Hakim, the chief of the Supreme Council for the Islamic Revolution in Iraq party.

He escaped unscathed but 13 people were killed and scores wounded. No one claimed responsibility for the attack but SCIRI spokesman Haitham al-Husseini blamed Saddam's old Baath party for the attack.

Hakim is the top candidate in the Shia coalition grouping called the Unified Iraqi Alliance, which is the early election favourite due to its endorsement from Grand Ayatollah Ali al Sistani, the most revered religious figure in Iraq.

The Democratic Party of the Iraqi Nation said the home of its secretary general, Mithal Al Alusi, was shelled in an assassination attempt on Monday. In a major blow to US and Iraqi government efforts to attract a strong role of the Sunnis in the election, the community's main party announced on Monday it would not be taking part.

"We are obliged to pull out," party chief Mohsen Abdel Hamid told reporters, saying the decision was motivated by the refusal of authorities to postpone elections for six months to ensure broader participation and to better control the security situation. -AFP