Court documents indicate that the summonses were issued as part of an IRS examination to determine Grant Thornton's compliance with tax shelter registration and list maintenance requirements, the Justice Department said in a prepared statement.

The revenue service's multi-pronged strategy to crackdown on tax shelters includes auditing taxpayers and promoters to ensure that they have complied with tax obligations. Accounting firms are required to identify taxpayers who may have invested in potentially abusive transactions organized and sold by the firm.

"Today's action is part of continuing IRS efforts to assure adherence with the law by promoters of potentially abusive tax avoidance transactions. Lawyers and accountants have a clear and established obligation to comply with the law requiring registration of tax shelters. We will resort to summons enforcement where necessary to compel compliance," said IRS Commissioner Mark Everson.

On Monday, in a speech delivered to mutual fund accountants, Public Company Accounting Oversight Board member Daniel Goelzer said the audit board may get involved in the tax shelter reform effort.

"I have no problem with auditors assisting their clients with traditional tax compliance and routine planning," Goelzer said, adding, "Tax services that go beyond that -- especially the marketing to audit clients of novel, tax-driven, financial products -- raise serious issues."

Goelzer said that tax planning is a "well-publicized congressional and public concern" and that the PCAOB "may have to try its hand at solving the problem."