(Reuters) - Banks seized more than a million U.S. homes in one year for the first time last year, despite a slowdown in the last few months as questions around foreclosure processing arose, a leading firm said on Thursday.

Banks foreclosed on 69,847 properties in December, bringing the year's total to 1.05 million, topping the prior record of 918,000 homes seized in 2009, real estate data firm RealtyTrac said.

The number of foreclosure filings, which includes default notices, auctions and repossessions, was a record 2.9 million last year, including 257,747 filings in December.

"Total properties receiving foreclosure filings would have easily exceeded 3 million in 2010 had it not been for the fourth-quarter drop in foreclosure activity -- triggered primarily by the continuing controversy surrounding foreclosure documentation and procedures that prompted many major lenders to temporarily halt some foreclosure proceedings," said James J. Saccacio, chief executive officer of RealtyTrac.

"Even so, 2010 foreclosure activity still hit a record high for our report, and many of the foreclosure proceedings that were stopped in late 2010,-which we estimate may be as high as a quarter million, will likely be re-started and add to the numbers in early 2011," Saccacio said.

December filings were 2 percent lower than November and 26 percent lower than December 2009.

The firm said Nevada, Arizona and Florida continued to post the highest foreclosure rates in the country.

And just five states -- California, Florida, Arizona, Illinois and Michigan -- accounted for more than half of all foreclosure activity.

One in every 11 housing units in Nevada received at least one foreclosure filing in 2010, more than four times the national average.

In 2005, before the housing bust, banks took over just about 100,000 houses, according to the Irvine, California-based company.