BAGHDAD A suicide bomber detonated a car packed with explosives at an Iraqi army checkpoint north of Baghdad on Tuesday, killing at least three people, police said, in an apparent attempt to destabilise the Shi'ite-led government.
The blast in Taji, 20 km (12 miles) north of the capital, followed another suicide attack in the same town a day earlier that killed at least 22 people.
It was the eighth suicide bombing in a month in Iraq, where insurgents are seeking to inflame tensions between Shi'ite, Sunni and ethnic Kurdish factions a year after U.S. troops pulled out of the country.
"There were patches of blood, pieces of clothing and shoes scattered around the place," said policeman Furat Fleh, whose patrol was near the checkpoint at the time of the blast. "We heard shooting and shouting after the explosion".
Prime Minister Nouri al-Maliki, a Shi'ite, has been struggling to quell mass protests by Sunni Muslims against what they see as the marginalisation of their sect since the fall of Saddam Hussein and the empowerment of Iraq's Shi'ite majority through the ballot box.
Ten years on from the U.S.-led invasion of Iraq, sectarian and ethnic divisions run deep.
Violence has fallen from the height of inter-communal slaughter that killed tens of thousands in 2006-2007, but insurgents have still been carrying out at least one high-casualty attack a month since the U.S. withdrawal in December 2011.
Unrest in Iraq's Sunni heartland is compounding fears the war in neighbouring Syria - where Sunni rebels are fighting to topple a leader backed by Shi'ite Iran - could further upset Iraq's own delicate sectarian and ethnic balance.
Thousands of Sunni protesters have taken to the streets since late December, rallying mainly in the Sunni-dominated Anbar province where they have blocked a highway to Jordan and Syria.
Many demonstrators want the government to amend anti-terrorism laws that Sunnis believe authorities misuse to target them, but hardliners and Sunni Islamists have called for Maliki to step down and even for an autonomous Sunni fiefdom inside Iraq.
Al Qaeda's Iraq affiliate, which views Shi'ites as apostates, last month called on Sunni protesters to take up arms against the government.
No group claimed responsibility for Tuesday's blast, but suicide bomb attacks are the hallmark of Iraq's local al Qaeda wing, Islamic State of Iraq, which has sent Sunni Islamist fighters and arms into Syria.
Iraq is home to a number of other Sunni insurgent groups.
(Writing by Isabel Coles)