Sen. Chuck Grassley is asking federal investigators to give him the names of officials at the American Red Cross who did not cooperate with the government's recent inquiry into the charity.

Grassley, an Iowa Republican, sent a letter to the Government Accountability Office Monday morning saying that the Senate Judiciary Committee, which he heads, "has received additional information that Red Cross personnel did not provide unfettered access to the GAO even after multiple requests for relevant information."

Grassley is asking investigators for a list of all the documents the GAO requested but "the Red Cross refused to provide," any records or emails the charity wrote that cite reasons for not providing records, and "a list of all the officials that did provide the material GAO requested."

"The Red Cross is a federal instrumentality created by Congressional charter," Grassley wrote in the letter, "and receives millions of dollars every year from donors across the country. As such, the Red Cross should have shared as much information as possible in order for GAO to perform a complete and thorough study."

The GAO completed its inquiry this month finding that the Red Cross needs "regular, external, independent and publicly disseminated evaluations," after a string of problems in its disaster response and questions about how it spends donors' money. The GAO asked Congress to consider legislation — the strongest recommendation the GAO can make.

In a statement, a Red Cross spokeswoman said the charity cooperated with the inquiry. The statement says the charity "worked cooperatively with the GAO to address their questions, provide interviews with disaster services leadership, and share documents about our programs. We had discussions with the GAO and members of Congress about the purpose and intent of the GAO study so we could respond in a way that would meet their goals."

The GAO said earlier this month that it always strives for unfettered access to its records and documents but that it "did not get that in this case."

GAO spokesman Chuck Young says the office will review Grassley's request as it does whenever lawmakers ask for additional information and decide what can be made available. This process typically takes several weeks, he says.

The Red Cross' problems with the GAO inquiry date to at least last summer when Red Cross CEO Gail McGovern wrote a letter to Rep. Bennie Thompson, a Democrat from Mississippi who requested the inquiry, and asked him to "end the GAO inquiry," according to a copy of the letter obtained by NPR and ProPublica. McGovern gave the congressman her private cellphone number and asked that he not communicate with her in writing. Thompson called the request " unbelievable."

Thompson has introduced the American Red Cross Sunshine Act, which calls for regular outside audits of the charity and requires the Red Cross to open its books during all future GAO inquiries.

Copyright 2016 NPR. To see more, visit http://www.npr.org/.