BAGHDAD (Reuters) - A total of 4,471 civilians died in Iraq's festering "low-level war" with insurgents in 2012, the first annual climb in the death toll in three years, campaigners said on Tuesday.

The deaths, up from 4,059 in 2011, showed militant fighters were still bent on carrying out large-scale bomb attacks, said rights group Iraq Body Count (IBC) in its annual report.

Tensions between Shi'ite, Kurdish and Sunni factions in Iraq's power-sharing government have been on the rise this year and the civil war in neighboring Syria is whipping up sectarian tension across the region.

Insurgents pose a potent threat even though violence has fallen sharply since the height of inter communal slaughter that followed the 2003 U.S.-led invasion that toppled former President Saddam Hussein.

There has been at least one large bombing a month this year, usually targeting security forces, government offices or Shi'ite Muslims. The bloodiest day of 2012 was September 9, when more than 100 people were killed in series of bomb blasts.

"2012 marks the first year since 2009 where the death toll for the year has increased," IBC said in a statement.

"In sum the latest evidence suggests that the country remains in a state of low-level war little changed since early 2009, with a 'background' level of everyday armed violence punctuated by occasional larger-scale attacks designed to kill many people at once," it added.

A year after U.S. troops left, sectarian friction, as well as tension over land and oil between Arabs and ethnic Kurds, threaten renewed unrest and are hampering efforts to repair the damage of years of violence and exploit Iraq's energy riches.

In December, figures released by government showed 208 Iraqis were killed, including 55 policemen and 28 soldiers.

IBC said it has now recorded between 110,937 and 121,227 civilian deaths in violent incidents since the 2003 invasion.

(Reporting by Ahmed Rasheed; Editing by Isabel Coles and Andrew Heavens)