BAGHDAD, Feb 25: Iraqi officials said at least 15 people were killed and dozens injured on Friday in violent clashes across the country between security forces and demonstrators.

Thousands of Iraqis took to the streets on Friday to vent their anger at government corruption, a lack of services and unemployment in the largest outpouring of anger in Iraq since the protests began sweeping the Middle East.

Security forces used water cannons and tear gas to disperse thousands of angry protesters in Baghdad. Around 5,000 demonstrators thronged Baghdad's Tahrir Square, with crowds of them angrily throwing stones, shoes and plastic bottles at riot police and soldiers blocking off a bridge connecting the rally site to Baghdad's heavily-fortified Green Zone, home to the US embassy and parliament.

The protest was the biggest of 17 separate demonstrations across the country, some sparking clashes that left more than 100 people injured, according to a tally based on accounts by officials.

At least four government buildings were set ablaze and one provincial governor resigned.

By 5.30pm most of the crowd in Baghdad had left and security forces refused to allow anyone to enter the area surrounding the square.

During the protest, demonstrators overturned two concrete blast walls on Jumhuriyah bridge, spurring lines of anti-riot police and soldiers to assemble, blocking it off.

Security personnel were deployed in force, imposing a city-wide vehicle ban after Prime Minister Nuri Al-Maliki claimed Al Qaeda militants and loyalists of deposed dictator Saddam Hussein organised the demonstrations.

Rallies in Iraq have called for improved public services, more jobs and less corruption, and some for broader political reforms.

Rated the fourth-most corrupt country in the world by Transparency International, Iraq suffers from poor electricity and water provision, as well as high unemployment nearly eight years since the 2003 US-led invasion.

MP Sabah Al-Saadi, who turned up at the Baghdad protest, was met with shouts and jeers, with one protester asking: Why are MPs taking millions of dinars (thousands of dollars) in salaries?

However, attendance at the Baghdad protest, which had been expected to draw tens of thousands, was partially muted by the fact that several religious leaders asked their followers not to attend. Radical cleric Moqtada Al-Sadr, in particular, said his partisans should give the government, of which his bloc is a key member, six months to improve on its record.

Friday's rally, like ones across the region, was largely organised on social networking website Facebook and billed as Iraq's day of rage, in reference to events in Egypt that forced out president Hosni Mubarak.

In the north, clashes between security forces and demonstrators in the cities of Mosul and the town of Hawija left seven dead. A 15-year-old boy also died in the mostly Kurdish town of Kalar in central Diyala province, while another person was killed in Samarra.

Protesters set fire to provincial government offices in Mosul and the city council building in Hawija, as well as two official buildings in Fallujah, west of Baghdad.

In the port city of Basra, the provincial governor resigned after 3,000 protesters gathered, while crowds chanted, Liar, liar, Maliki! in the southern cities of Nasiriyah, Karbala and Kut.

In a bid to head off protests, Iraq slashed politicians' pay, increased food funds for the needy and delayed a planned law that would raise import tariffs and, thus, prices of goods in markets.—Agencies