Prosecutors in the US Justice Department under former president Donald Trump seized data from Apple from two Democratic representatives on the House Intelligence Committee, as well as that of their staff and family members.
The New York Times reported on Thursday that subpoenas for communications metadata were issued for Adam Schiff of California, a Trump foe who was then the panel's top Democrat and now its chairman.
The record seizures came in 2017 and early 2018 as the department investigated leaks of classified information relating to contacts between the Trump administration and the Russian government, the paper reported.
Eric Swalwell told CNN on Thursday that he was the second Democratic member of the committee who was investigated.
"I was notified ... by Apple that they did seize my records. It's wrong," he said.
One of the family members under investigation was a minor, The New York Times reported.
Prosecutors working under then attorney general Jeff Sessions made unusual efforts to find the source of the leaks of classified information.
Justice Department officials collected electronic data not only from the Mr Swalwell and Mr Schiff, but from their staff and families, with investigators believing the congressmen were using their associates' or children's devices to hide contacts with journalists.
The Justice Department and Apple have yet to comment on the report.
Ultimately, none of the data or other evidence tied the congressmen or the House Intelligence Committee to the leaks, The New York Times said.
But the leak investigations were revived by former attorney general Bill Barr a year later, the paper reported.
The seizure of such records has rarely been seen outside of corruption investigations.
Mr Schiff, while not confirming he was a target of the investigation, called for a probe by the Justice Department's inspector general into "this and other cases that suggest the weaponisation of law enforcement by a corrupt president".
Mr Trump "tried to use the department as a cudgel against his political opponents and members of the media. It is increasingly apparent that those demands did not fall on deaf ears," Mr Schiff said in a statement.
Democrat Nancy Pelosi also called for an investigation, describing the report as "harrowing".
"These actions appear to be yet another egregious assault on our democracy waged by the former president," she said in a statement.
The Justice Department placed a gag order on Apple that expired this year, meaning members of Congress were unaware of the probes until the tech company notified them last month, the paper said.
Mr Schiff, a leader on the Democratic impeachment team, has long railed against Mr Trump, calling him "dangerous".
He made the case in early 2020 for Mr Trump to be removed from office for abuse of power and obstruction of Congress.
Mr Trump was subsequently impeached twice and defeated after a single term, but returned to the spotlight last week for his first speech in months, framing next year's midterm elections as a battle for the "survival of America".
The House of Representatives impeached Mr Trump in 2019 for pressuring Ukraine to investigate his political opponents, dangling military aid to Ukraine and a White House visit in return.
He was then acquitted in the Senate this year on an impeachment charge of inciting the January 6 attack on the US Capitol by his supporters.
A two-thirds majority was needed in the 100-member Senate to convict Mr Trump but only 57 senators voted "guilty".
Seven Republicans joined Democrats in the Senate in voting to convict the former president.
