Violence in Iraq caused the deaths of more than 15,000 civilians and security personnel in 2014, government figures show, making it one of the deadliest years since the 2003 US-led invasion.

Last year's toll of 15,538 was more than double the 6,522 people killed in 2013.

It was the worst in seven years, the Iraqi government said, almost reaching the toll of 17,956 during the height of Sunni-Shiite sectarian killings in 2007.

The UN put the number of civilians killed in Iraq during 2014 at 12,282.

"Yet again, the Iraqi ordinary citizen continues to suffer from violence and terrorism. 2014 has seen the highest number of causalities since the violence in 2006-2007," UN Iraq envoy Nickolay Mladenov said in a statement.

"This is a very sad state of affairs."

Iraq Body Count, a Britain-based NGO that tracks violence in Iraq, gave an even higher toll for 2014, saying 17,073 civilians were killed, which would make it the third deadliest year since 2003.

"For Iraqis, it has been the most difficult and painful of years because of the attack of the [Islamic State group] terrorist gangs," prime minister Haider al-Abadi said in a New Year's speech, referring to jihadists responsible for much of the bloodshed in the north and west of the country.

In nearby Syria the death toll from the conflict was even higher.

A monitoring group said 17,790 civilians died in 2014, including 3,501 children.

The Syrian Observatory for Human Rights said it had documented the deaths of 76,021 people in total.

That figure included 22,627 government forces and members of pro-government militias, more than 15,000 rebel fighters and nearly 17,000 militants from jihadist groups, including Islamic State and Al-Nusra Front, Al Qaeda's Syrian affiliate.

This made it the deadliest year in the nearly four-year war, the British-based observatory said.

There were 73,447 deaths in 2013, 49,294 in 2012 and 7,841 in 2011, the observatory said.

More than 200,000 people have been killed since the conflict began in March 2011 with anti-regime protests that spiralled into a war after a government crackdown.

Advance of Islamic State across Iraq, Syria to blame for rise

The year got off to a bloody start when the government lost control of parts of the Anbar provincial capital Ramadi and all of Fallujah - just a short drive from Baghdad - to anti-government fighters.

The violence was sparked by the demolition of the country's main Sunni Arab anti-government protest camp near Ramadi in late 2013.

It spread to Fallujah, and security forces later withdrew from areas of both cities, leaving them open for capture.

Then in June Islamic State fighters spearheaded a major offensive that swept security forces aside.

Militants overran Iraq's second city Mosul and then drove south towards Baghdad, raising fears that the capital would be attacked.

They were eventually stopped short of the capital, but seized swathes of five provinces north and west of the city.

A renewed IS push in the north in August drove Kurdish forces back towards the capital of their autonomous region, helping to spark a US-led campaign of air strikes against the jihadists

That effort had expanded to training for Iraqi forces aimed at preparing them as quickly as possible to join the fight against IS.

Iraqi soldiers and police, Kurdish forces, Shiite militias and Sunni tribesmen have succeeded in regaining some ground from the jihadists.

But large parts of the country, including three major cities, remain outside Baghdad's control.

AFP