The state of Maryland is suspending part of its contribution to the Washington Metropolitan Area Transit Authority until agency officials comply with the state’s audit requests.

Maryland Secretary of Transportation Pete Rahn sent a letter to the Metro’s Board of Directors Monday stating that the state will not deliver more than $55 million, or about a quarter, of its capital funding to the transit system, accusing the agency of “stonewalling” on compliance audits, The Washington Post reported Monday. WMATA relies on capital funds to conduct maintenance and purchase new rail cars and equipment.

“This is the latest unfortunate, but necessary, step the state of Maryland believes it must take in response to an ongoing pattern of fiscal obfuscation and lack of cooperation from WMATA,” the letter states.

The move comes as Maryland prepares to increase its annual subsidy to the Metro from $467 million in 2017 to $741 million in 2020, according to The Post.

Rahn said in the letter that WMATA officials were unwilling to comply with the Maryland Department of Transportation’s attempts to audit the transit agency, The Post reported. MDOT is required by Maryland law to audit WMATA annually, but WMATA has ignored Maryland’s requests and directed state officials to its own independent annual audit, WAMU reported Monday.

Rahn added that WMATA officials have also “refused to offer details of the methodology they used to calculate the operating subsidy” that Maryland pays to the Metro, according to The Post. MDOT’s Office of Audits recently found that WMATA miscalculated Maryland’s subsidy, leading to a reduction in payment by about $1.3 million, the letter states.

That subsidy, which Maryland provides to WMATA for the Metro’s daily operation, will not be affected by the move, The Post reported.

“WMATA’s books cannot continue to be a financial black hole, absorbing every dollar it can but providing no information or data that Marylanders expect from public institutions,” the letter states.

Metro spokesman Ian Jannetta told The Post that Metro officials “will meet with Maryland officials as soon as possible to fully understand and address the issues raised in their letter.”