House Republicans on Tuesday accused officials at the National Institutes of Health of orchestrating “a conspiracy at the highest levels” of the agency to hide public records related to the origins of the Covid pandemic. And the lawmakers promised to expand an investigation that has turned up emails in which senior health officials talked openly about trying to evade federal records laws.

The latest accusations — coming days before a House panel publicly questions Dr. Anthony S. Fauci, a former top N.I.H. official — represent one front of an intensifying push by lawmakers to link American research groups and the country’s premier medical research agency with the beginnings of the Covid pandemic.

That push has so far yielded no evidence that American scientists or health officials had anything to do with the coronavirus outbreak. But the House panel, the Select Subcommittee on the Coronavirus Pandemic, has released a series of private emails that suggest at least some N.I.H. officials deleted messages and tried to skirt public records laws in the face of scrutiny over the pandemic.

Even those N.I.H. officials whose job it was to produce records under the Freedom of Information Act may have helped their colleagues avoid their obligations under that law, several emails suggest. The law, known as FOIA, gives people the right to obtain copies of federal records.

“I learned from our foia lady here how to make emails disappear after i am foia’d but before the search starts, so i think we are all safe,” Dr. David Morens, a former senior adviser to Dr. Fauci, wrote in February 2021. That email chain included Dr. Gerald Keusch, a scientist and former N.I.H. official, and Peter Daszak, the president of EcoHealth Alliance, a virus-hunting nonprofit group whose work with Chinese scientists has drawn scrutiny from lawmakers.

“Plus i deleted most of those earlier emails after sending them to gmail,” Dr. Morens added, referring to his personal Gmail account.

In another email, about an editorial he was helping to prepare in July 2020, Dr. Morens reassured his collaborators that sending notes about a sensitive government grant to his official email account was OK because “I have spoken to our FOIA folks” and “I should be safe from future FOIAs.” He added: “Don’t ask how….”

Those emails came from Dr. Morens’s personal email account, which the House panel subpoenaed last month and which lawmakers have accused Dr. Morens of using to avoid public records disclosures.

House Republicans released additional emails on Tuesday that they said implicated a second N.I.H. official in what they described as efforts to evade public records laws.

In one of those emails, from June 2021, Greg Folkers, a former chief of staff to Dr. Fauci, was discussing global biosafety practices and referred to a fact sheet from EcoHealth. Mr. Folkers rendered the group’s name as “Ec~Health,” a misspelling that lawmakers said appeared to be a deliberate attempt to keep the email from being caught in keyword searches to fulfill FOIA requests related to EcoHealth.

In a separate email from the same month, Mr. Folkers rendered the last name of Kristian Andersen, a prominent virologist who has investigated the origins of the pandemic and has faced scrutiny from lawmakers, as “anders$n.”

Experts on record retention policies said the comments were reflective of poor transparency practices across federal government agencies, with officials strategically misspelling words in emails, missing deadlines for responding to records requests and using personal email addresses to evade records laws.

And suggestions in the N.I.H. emails that the agency’s federal records office was coaching officials on how to subvert the law, they said, were an even more extreme departure from best practices.

“I’ve very rarely seen an agency’s FOIA office trying to help staff work around or avoid their obligations,” said Michael Morisy, chief executive of the nonprofit news website MuckRock, which helps file and track public records requests. If federal records officials were indeed helping their N.I.H. colleagues make emails disappear, Mr. Morisy said, “that’s really damaging to trust in all of government.”

A spokeswoman for the Department of Health and Human Services, of which N.I.H. is a part, did not respond to questions about the agency’s FOIA office, but said in a statement that department policy forbids employees from using personal email accounts to do official business.

“H.H.S. is committed to the letter and spirit of the Freedom of Information Act and adherence to federal records management requirements,” the statement said.

Timothy Belevetz, a lawyer for Dr. Morens, said in a statement, “Dr. Morens has a demonstrated record of high quality and important contributions to science and to public service.”

At a hearing of the House panel last week, Dr. Morens, who is on administrative leave from the N.I.H., denied that the agency had instructed him on how to avoid records laws and apologized for some of his emails, saying that he thought they were private comments to friends.

Attempts to reach Mr. Folkers, who left the N.I.H. last year, were unsuccessful. Dr. Keusch has called the House panel’s accusations “dangerous to science.” Dr. Daszak has rejected allegations that he had withheld documents related to the origins of the pandemic.

The record-keeping revelations grew out of the House panel’s investigations into the origins of the Covid pandemic, a bitterly contentious issue that has drawn more attention from lawmakers as they prepare for elections this year. Many of the emails concern contact between N.I.H. officials and EcoHealth, whose lapses in handling government grants have generated bipartisan anger and led to a proposal last week to bar it from federal funding.

The recently released emails — including those that N.I.H. officials wrongly believed would be safe from outside scrutiny — do not lend additional weight to theories that N.I.H.-funded lab work in China led to the Covid outbreak. In several emails, N.I.H. officials and scientists fretted that the disclosure of their emails and discussions of “political attacks” could come back to hurt them.

In another note, Dr. Morens lamented the news media’s role in elevating lab leak theories and said that scientists willing to push back on those theories “don’t speak out for fear they will be attacked too.” He was defending the idea that the pandemic had started instead at an illegal wild-animal market in China, a theory that scientists have said is supported by early cases and viral genomes.

It remains unclear what may be in emails that have not yet been disclosed, including those from another private account of Dr. Morens’s that House Republicans say he started using after they had begun seeking his emails.

The House panel is also investigating Dr. Fauci’s record-keeping practices. Dr. Morens’s emails make reference to using Dr. Fauci’s “private gmail” as a way of avoiding federal records laws.

Scott Amey, the general counsel at the nonpartisan Project on Government Oversight, said record-keeping practices like those being ascribed to the N.I.H. set back attempts to improve the functioning of government, calling the conduct “extremely concerning.”