WASHINGTON (January 17, 2013)--A government watchdog says the IRS detected more than 173,000 fraudulent tax returns from prison inmates last year, more than twice the number of fraudulent returns from inmates in 2010.

Many of the inmates were using stolen identities and other false information in an attempt to get tax refunds.

In all, the IRS says it stopped inmates from illegally claiming $2.5 billion in tax refunds in the 2012 budget year.

Just two inmates claimed about $1.1 billion of that.

The inspector general for tax administration credits the IRS and prison officials with stepping up enforcement and sharing more information, but says more can be done.