The number of homes taken over by banks topped 100,000 for the first time in September, though foreclosures are expected to slow in coming months as lenders work through questionable paperwork, real estate data company RealtyTrac said on Thursday.

Banks foreclosed on 102,134 properties in September, the first single month above the century mark, RealtyTrac said. There were 347,420 total foreclosure filings in September, 3 percent higher than August and 1 percent higher than a year earlier.

"We expect to see a dip in those bank repossessions -- and possibly earlier stages of the foreclosure process -- in the fourth quarter as several major lenders have halted foreclosure sales in some states while they review irregularities in foreclosure-processing documentation that has been called into question in recent weeks," said James J. Saccacio, chief executive officer of RealtyTrac.

On Wednesday, all 50 states launched a joint investigation of the mortgage industry after widespread reports of mortgage industry officials signing foreclosure documents without knowing their contents.