A Senate committee is seeking thousands of pages of internal documents from the Nature Conservancy as part of an "independent review" of the charity's practices.

In a letter sent yesterday to Conservancy President Steven J. McCormick, the Senate Finance Committee asked for records reaching back a decade and spanning 18 broad topics. Along with general explanations of Conservancy policies, the committee is requesting information as detailed as the Social Security numbers of individuals who received loans and land from the nonprofit.

The letter is signed by committee Chairman Charles E. Grassley (R-Iowa) and ranking Democrat Max Baucus (Mont.). The senators said in May that they might consider legislation after The Washington Post reported on a range of Conservancy practices, including the group's sale of scenic property to trustees who then made tax-deductible donations to the organization.

In the seven-page letter to the Nature Conservancy, the senators cite "serious questions about TNC's practices regarding land sales, purchases and donations; executive compensation; and corporate governance, among others."

As part of its review, the committee plans to seek information independently about the Conservancy from the Internal Revenue Service, a committee staff member said yesterday.

The Arlington-based Conservancy said in a statement that it "has been in discussion with Committee staff, and has conveyed to them that the Conservancy will work cooperatively and expeditiously with the Committee to address all matters within the scope of the inquiry."

The Conservancy also pointed out that, independent of the inquiry, the group had thoroughly reviewed its practices, and its board of governors had made several changes.

The Senate letter includes more than 100 questions and requests for information, some of which could elicit hundreds of pages in response.

The letter asks for information on all of the Conservancy's land deals with private individuals, including so-called "conservation buyer" deals. In those deals, the Conservancy bought raw land, added development restrictions, then resold the land at a reduced price. The buyers then made tax-deductible gifts to the nonprofit.

Many of the conservation buyers were current or former Conservancy trustees, who built homes on the rustic sites. When the Conservancy board announced major policy changes on June 13, it included a prohibition on land sales to trustees and other Conservancy insiders.

The committee wants to examine details of all loans the Conservancy has made in the past decade, including those extended to a power company and other for-profit corporations. Its request covers a dozen home loans to Conservancy employees, including $1.5 million extended to McCormick and a no-interest $500,000 mortgage extended to California state director Graham Chisholm.

The senators also want to examine all audits of Conservancy operations from the past five years. The committee seeks details of land sales to government agencies, including appraisals and any profits banked by the Conservancy. In particular, the letter asks for a list of grants and contracts involving three nonprofits: the National Fish and Wildlife Foundation; the National Forest Foundation; and the National Park Foundation.

The committee asked that the material be submitted within a month.