WASHINGTON — The office that receives complaints from Congressional staffers on sexual harassment has refused to release information on settlements in the Senate, keeping secret the amount of taxpayer money spent to quiet such claims.

Sen. Tim Kaine, D-Va., asked the Office of Compliance on Dec. 6 to release the number of sexual harassment claims filed against a senator or his or her staff between 2007 and 2017. He also asked for the dollar amounts of the settlements and said he would make the information public.

In a response Monday provided to NBC News by Kaine's office, the OOC said it was unable to release the information, citing a number of reasons that included confidentiality requirements.

Sen. Tim Kaine, D-Va., listens to testimony during a Senate Foreign Relations Committee hearing on Capitol Hill on Dec. 6, 2017. Drew Angerer Getty Images

Susan Grundmann, executive director of the OOC, said in a letter that the Congressional Accountability Act, the statute that created the Office of Compliance, prohibits her from releasing the data.

"Earlier this month the OOC provided the Senate Committee on Rules and Administration with a statistical breakdown of settlement amounts involving Senate employing offices from 1997-2017. That information represents the full extent of what we can provide with regard to settlements under the CAA involving the Senate," Grundmann wrote. "Any additional disclosure would involve an invasive search of strictly confidential records, which would be contrary to existing law."

Related: Rep. Blake Farenthold settled sexual harassment claim for $84,000

Grundmann also wrote that the data would be incomplete and, therefore, unreliable because she said specifics aren't documented on why a case advances through the settlement process.

She also said her office doesn't have records of all the accounts where settlements are paid beyond the U.S. Treasury. "If some other accounts used to make a payment, we would not necessarily know about the settlement," Grundmann wrote. She directed Kaine to the Secretary of the Senate, which she says has "more detailed and accurate" information.

Kaine, who told Grundmann in his original request that he'd make the information public, wasn't satisfied with Grundmann's response. In a statement, Kaine said that by not releasing the names of the accused or the accusers, no privacy rights would be violated.

"If Congress truly wants to fix a broken system, we need to understand the scope of the problem. I'm disappointed the OOC didn't release any information to help us do that," Kaine said in a statement. "I'm going to keep pushing for public release of this data and working on reforms that help prevent harassment and assault."

Related: Farenthold drops re-election bid amid harassment claims

The OOC's response seems to be inconsistent. The office released five years of data in settlements with House offices to the House Administration Committee and is expected to release the first 15 years as well.

The only public information surrounding Senate settlements is a $220,000 payment in 2014 between the bicameral Helsinki Commission and an employee. Even rough the accused was a congressman, Rep. Alcee Hastings, D-Fla., the case was finally resolved with the Senate Chief Counsel for Employment office.

The House data revealed that one $84,000 settlement was reached since 2013. While the OOC didn't release the name of the accused, NBC News confirmed that the settlement was invloving Rep. Blake Farenthold, R-Texas. Farenthold announced last week he would not seek re-election.