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BAGHDAD, Jan 31 (Reuters) - The number of U.S. soldiers and Iraqi civilians killed in attacks in January fell to the lowest level since the 2003 U.S.-led invasion, data showed on Saturday.

Iraqi government figures showed 138 civilians were killed in January, lower than the 238 people killed in each of the months of December and October, previously the lowest monthly tolls.

In January last year 466 Iraqi civilians were killed.

Four U.S. soldiers died in combat during January this year, also the lowest figure since the invasion in March 2003, according to www.icasualties.org, which collates official data.

The previous lowest figure was seven U.S. soldiers killed in December last year.

The sectarian violence and insurgency unleashed by the invasion to topple Saddam Hussein has fallen dramatically in the past year, even as al Qaeda and other insurgent groups continue to carry out devastating suicide and car bomb attacks.

Iraq on Saturday held its most peaceful election since the fall of Saddam. The vote to pick regional councils in 14 of the country's 18 provinces passed without a single major attack being reported.

Since the invasion a total of 4,236 U.S. soldiers have died in Iraq, or in surrounding areas where troops are stationed, including those killed by non-hostile causes such as accidents or illness.

At least 90,554 civilians had been killed up to Jan. 21, according to www.iraqbodycount.net. (Writing by Michael Christie; Editing by Charles Dick)

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