The Environmental Protection Agency's (EPA) inspector general is pushing back on a legal opinion from EPA lawyers that minimized their responsibility to comply with investigations, the latest tit-for-tat between the agency and its internal watchdog.

The EPA’s Office of Inspector General (OIG) had originally released a letter Wednesday tearing into the EPA’s highest ranking staff for “refusal to fully cooperate and provide information.”

The complaint centers on Ryan Jackson, the chief of staff to EPA Administrator Andrew Wheeler Andrew WheelerOvernight Energy: Trump officials finalize plan to open up protected areas of Tongass to logging | Feds say offshore testing for oil can proceed despite drilling moratorium | Dems question EPA's postponement of inequality training Democrats question EPA postponement of environmental inequality training OVERNIGHT ENERGY: California seeks to sell only electric cars by 2035 | EPA threatens to close New York City office after Trump threats to 'anarchist' cities | House energy package sparks criticism from left and right MORE, though the letter also criticized Wheeler for ignoring emails from the inspector general asking him to spur cooperation from Jackson. ADVERTISEMENT

The OIG's rebuke came in a rare “Seven Day Letter,” a term used to describe the process of notifying Congress of serious roadblocks to investigations.

That letter was initially sent to the EPA on Oct. 29, prompting Wheeler to ask the agency's general counsel for a legal opinion on their obligations for dealing with investigators.

The subsequent legal opinion released this week suggested that the EPA met their obligations by offering an interview with Jackson after the Seven Day Letter had already been drafted.

“Your attempts to accommodate the OIG, nonetheless, fulfilled your legal obligation,” general counsel Matthew Leopold wrote Tuesday.

But the latest pushback from acting Inspector General Charles Sheehan said the legal opinion “grafts wide and wholesale evasions” on the law dictating inspector general investigations.

“He offers free rein to agency staff to refuse OIG requests for information,” Sheehan said of Leopold, adding that the “interpretation of the General Counsel subverts our independence.”

OIG investigators were trying to meet with Wheeler’s chief of staff to discuss how he obtained an advanced copy of testimony designated for lawmakers, a move that could be considered interfering with or intimidating individuals who testify before Congress.

But Jackson refused to answer the questions or sit down for an additional interview with investigators.

“Will I say where I got it from? No," he said in an Oct. 3 interview.

In an email a few weeks later reviewing his refusal to sit down again with investigators, he wrote, “I am not going to involve others or point fingers.”

Politico also reported Thursday that Jackson is under investigation to determine whether he was involved in destroying EPA documents that should have been retained.

The latest letter from the OIG — which is dated Thursday and was released Friday — picks apart the general counsel legal opinion point by point, in some cases noting the “authority” referenced in the letter came from “a single, dissenting judicial opinion” or a legal brief.

Sheehan also said the legal opinion “misconstrues facts” by claiming EPA was in the process of complying with investigators when the Seven Day Letter was sent.

“There was no agency accommodation 'progress' whatsoever—quite the opposite—by the time the Seven Day Letter was issued. As detailed in the Seven Day Letter, the OIG made repeated, fruitless attempts over weeks and months, including OIG elevation to the Administrator, Associate Deputy Administrator and General Counsel, in writing and in person, to produce Mr. Jackson’s audit and investigation cooperation,” Sheehan wrote.

The EPA later Friday produced a new memo from its general counsel.

"I have considered these issues, and nothing in the acting inspector general's reply warrants a revision to the fundamental conclusions," Leopold wrote, though he attached an updated version of the memo "with the hope of narrowing the precise legal dispute and preventing my advise from being further mischaracterized by OIG, or in the future by the agency."

A spokesman for the EPA defended its memo.

“EPA’s General Counsel’s memo lays out the Agency’s obligations. EPA has attempted to provide assistance to the Office of Inspector General, and we will continue to do so,” the agency said in an email before again expressing frustration that the Seven Day Letter was released at all.

“The Acting Inspector General’s decision to continue with the Seven Day Letter is troubling in light of the assistance the Agency provided and undermines the cooperative and iterative relationship that EPA has shared with its OIG.”

The House Committee on Science, Space and Technology, which oversees the EPA said they will look into the issue as they inch closer to issuing a subpoena for other documents from the agency.

“It was an indication of our deep concern when the Committee felt it necessary to request that the EPA OIG open an investigation into possible interference by a political employee with a federal scientist’s testimony before Congress. To see that the same high level political employee may be refusing to comply with the Inspector General’s investigation is even more concerning," Chair Eddie Bernice Johnson Eddie Bernice JohnsonHillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll House passes legislation to boost election security research Hillicon Valley: Twitter flags Trump campaign tweet of Biden clip as manipulated media | Democrats demand in-person election security briefings resume | Proposed rules to protect power grid raise concerns MORE said in a statement to The Hill.

Updated at 3:29 p.m.