(Bloomberg News) Women age 65 and older live in poverty at higher rates than men even as more of them participate in employer-sponsored retirement plans, according to a U.S. Government Accountability Office study.

The median income for women in that age group was about 25 percent lower than for men between 1998 and 2009, and the women were twice as likely to be living in poverty, according to the report titled Retirement Security: Women Still Face Challenges.

Retired women continue to rely on Social Security at higher rates than retired men, with 16 percent of women and 12 percent of men age 65 and older depending on Social Security as their only income in 2010, according to the report.

"Several factors contribute to the higher rate of poverty among elderly women including their tendency to have lower lifetime earnings, take time out of the workforce to care for family members, and outlive their spouses," according to the study.

While women's participation in defined-contribution retirement plans increased, they contributed less to those plans than men did, according to the study.

Divorce and widowhood had "detrimental effects" for retired women or those entering retirement, and took more of a toll on women's finances than on men's, the study found.