The Internal Revenue Service has increased its audits of taxpayers at upper-income levels.

According to IRS statistics released on Thursday, 12.48 percent of taxpayers with income of $1 million or higher were subjected to audits in fiscal year 2011, compared to 8.36 percent in fiscal year 2010. Those with incomes of $200,000 or higher were audited at a rate of 3.93 percent in fiscal year 2011, compared to 3.10 percent in fiscal year 2010.

In contrast, 1.02 percent of taxpayers with incomes below $200,000 a year were audited in fiscal year 2011, compared to 1.04 percent in fiscal 2010.

Large corporations were also audited at a higher rate last year, with 17.6 percent of those with assets of $10 million and higher audited in fiscal 2011, compared to 16.6 percent in fiscal year 2010.

Those with assets of $250 million and higher were audited at a rate of 27.6 percent in fiscal 2011, compared to 25.3 percent in fiscal 2010.

Smaller corporations with assets under $10 million were also audited at a greater rate, with examinations of 1.02 percent of them in fiscal 2011, compared to 0.94 percent in fiscal 2010.