A top D.C. lawmaker said she's concerned about an effort by Mayor Vincent Gray's administration to tighten the city's open records law, a move that would reduce the number of documents available to the public at a time when District officials -- including Gray -- are the subjects of criminal probes.

"It would appear that the mayor's proposal backtracks," said Ward 4 Councilwoman Muriel Bowser, who chairs the council committee that handles Freedom of Information Act, or FOIA, matters.

District law already prevents some documents from public disclosure, but the administration's proposal would expand the roster of exemptions. For example, if lawmakers or the mayor requested that a nonprofit organization conduct a study on the city's behalf, the results could be withheld from the public in some circumstances.

The measure would also extend the amount of time that the city has to comply with open records requests. District agencies currently have 15 business days to respond, but that window would expand to 20 days under Gray's proposal.

D.C. Attorney General Irvin Nathan, who crafted the revised open records law on Gray's behalf, said the administration is pushing for an overhaul to streamline city government and "limit abuse by some FOIA requesters."

"The current FOIA system is hurting the effectiveness of the District government, and reform is needed," Nathan said in a statement. The District's open records process is an active one, with nearly 5,700 requests filed during the 2011 fiscal year. The city fully or partially granted 71 percent of those requests.

The proposed changes come as federal investigators continue probing corruption in city politics.

Gray's 2010 campaign is under scrutiny for allegedly paying a fringe mayoral candidate to remain in the race and criticize Gray's political archrival, former Mayor Adrian Fenty. Two of Gray's campaign aides have already pleaded guilty in that case.

Thomas Susman, the president of the D.C. Open Government Coalition, said he would be surprised if lawmakers backed the changes as the investigations linger.

"It is inconceivable to me that given the current climate in the District, the council would buy into a wholesale dilution to the right to information," Susman said. "I don't think this is a legislative reality."

Examiner Staff Writer Liz Farmer contributed to this report.