The gap between the promises states have made for public employees' retirement benefits and the money they have set aside grew to at least $1.26 trillion in fiscal year 2009, resulting in a 26 percent increase in one year, according to a report released Tuesday by the Pew Center on the States.

According to Pew, the report's figures are likely conservative estimates because they reflect the states' own assumptions about the average investment returns they will achieve.

The report, The Widening Gap: The Great Recession’s Impact on State Pension and Retiree Health Care Costs is the most comprehensive analysis to date, covering pension, health care and other benefits promised to both current and future retirees. Researchers examined the funding performance of 231 pension plans and 162 other post-employment benefit plans.