A federal judge said Wednesday that the Environmental Protection Agency may have tried to evade a Freedom of Information Act request and added that “numerous inconsistencies” in the agency’s court filings “undermine confidence in their truthfulness.”

As a result, Judge Royce C. Lamberth granted the conservative Landmark Legal Foundation, which filed the request for e-mails of current and former top EPA officials, the right to question them in person and in writing.

“The possibility that unsearched personal email accounts may have been used for official business raises the possibility that leaders in the EPA may have purposefully attempted to skirt disclosure under the FOIA,” Lamberth wrote.

The foundation filed the request in a bid to determine whether former EPA administrator Lisa P. Jackson used a private e-mail account to conduct agency business outside public scrutiny. Congressional Republicans and two right-leaning organizations have hammered the EPA over the issue, and the agency’s inspector general is auditing the practice.

Jackson had a private e-mail account under the name “Richard Windsor,” derived from the names of her dog and her home town. The EPA has said that administrators have used private accounts for nearly two decades because their public accounts receive an overwhelming number of e-mails. Jackson received more than 1.5 million e-mails in fiscal 2012, an agency official has said.

The EPA asked Lamberth to throw out the FOIA request, but he instead granted Landmark the right to question Jackson and two other top officials about whether they used personal e-mail to conduct official business and whether the EPA initially tried to exclude them from the FOIA request.

Lamberth said in his opinion that “EPA did not search the personal email accounts of the administrator, the deputy administrator or the chief of staff.”

E-mails and phone calls to EPA spokespeople and Landmark’s offices were not returned.