Washington — House Speaker Nancy Pelosi slammed a classified briefing given Thursday by Treasury Secretary Steve Mnuchin as "stiff competition" for "one of the worst classified briefings we have received from the Trump administration."

She said the secretary "barely testified," and that the Treasury officials who accompanied him read from an unclassified document. The officials wound up "wasting the time of the members of Congress," Pelosi said, as she flipped through the document in her hands.

Mnuchin delivered the classified briefing to a bipartisan group of House members on the administration's decision to terminate sanctions against companies linked to Russian billionaire and Putin ally Oleg Deripaska. He was joined by senior officials from the department's terrorism and financial intelligence arm.

House Speaker Nancy Pelosi and Treasury Secretary Steve Mnuchin Getty

In subsequent remarks to reporters, Mnuchin said he was "somewhat shocked" by Pelosi's criticism as he said she didn't attend the entire briefing. He added he answered half of the questions and reminded reporters he "voluntarily" came to brief legislators two days after the request was made.

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His appearance came a week after Democrats officially assumed the majority and began flexing oversight and legislative muscle vis a vis the Trump administration.

On Tuesday, seven Democrat House chairmen sent Mnuchin a letter laying out their concerns about the agreement reached with Deripaska and requesting more details about why and how the sanctions termination was justified.

"[T]he agreement appears to keep intact significant ownership of EN+ by Mr. Deripaska, while reportedly transferring some share and financial interests to the Kremlin-linked sanctioned Russian bank VTB," they wrote.

Citing the ongoing government shutdown and the timing of Treasury's December announcement, they also requested the sanctions termination be delayed beyond the required 30-day window to allow for further review.

Senate Minority Leader Chuck Schumer last week filed a long-shot congressional resolution in an attempt to block the sanctions termination — it would require Republican support to pass.

Deripaska, his companies and dozens of other Russian businesses and government officials were hit with sanctions last April as part of the administration's retaliation for Moscow's actions in Ukraine and its interference in the U.S. political system.

According to the Treasury Department's announcement at the time, Deripaska was himself alleged to have engaged in money laundering, extortion and ordering the murder of a businessman, according to Treasury's announcement at the time.

Deripaska would remain subject to U.S. sanctions even if those applied to his companies are lifted. His links former Trump campaign chairman Paul Manafort are under continued scrutiny by special counsel Robert Mueller.

Manafort was indicted as part of the special counsel's ongoing investigation into links between Russia and the Trump campaign in October 2017. He is awaiting sentencing after pleading guilty to conspiracy against the United States.