White collar federal employees are underpaid on average by about 35 percent compared with the private sector, a widening of the “pay gap” that stood at about 26 percent last year, an advisory group said Friday.

The Federal Salary Council based that number on data from the Bureau of Labor Statistics that by law are supposed to be used in setting annual General Schedule pay raises that vary by locality. However, in practice federal pay raises are negotiated in the congressional budget process.

Salary rates have been frozen since they last were increased in January 2010 and it already has been decided that rates will not increase at least until April 2013.

Continue reading: Federal workers are falling farther behind on pay, study shows