Newly released documents reveal the National Security Agency improperly collected Americans’ call records for a second time, just months after the agency was forced to purge hundreds of millions of collected calls and text records it unlawfully obtained.

The document, obtained by the American Civil Liberties Union, shows the NSA had collected a “larger than expected” number of call detail records from one of the U.S. phone providers, though the redacted document did not reveal which provider nor how many records were improperly collected.

The document said the erroneously collected call detail records were “not authorized” by the orders issued by the Foreign Intelligence Surveillance Court, which authorizes and oversees the U.S. government’s surveillance activities.

Greg Julian, a spokesperson for the NSA, confirmed the report in an email to TechCrunch, saying the agency “identified additional data integrity and compliance concerns caused by the unique complexities of using company-generated business records for intelligence purposes.”

NSA said the issues were “addressed and reported” to the agency’s overseers, but did not comment further on the violations as they involve operational matters.

The ACLU called on lawmakers to investigate the improper collection and to shut down the program altogether.

“These documents further confirm that this surveillance program is beyond redemption and a privacy and civil liberties disaster,” said Patrick Toomey, a staff attorney with the ACLU’s National Security Project. “The NSA’s collection of Americans’ call records is too sweeping, the compliance problems too many, and evidence of the program’s value all but nonexistent.”

“There is no justification for leaving this surveillance power in the NSA’s hands,” he said.

Under the government’s so-called Section 215 powers, the NSA collects millions of phone records every year by compelling U.S. phone giants to turn over daily records, a classified program first revealed in a secret court order compelling Verizon — which owns TechCrunch — from documents leaked by whistleblower Edward Snowden. Those call records include the phone numbers of those communicating and when — though not the contents — which the agency uses to make connections between targets of interest.

But the government was forced to curtail the phone records collection program in 2015 following the introduction of the Freedom Act, the only law passed by Congress since the Snowden revelations which successfully reined in what critics said was the NSA’s vast surveillance powers.

In recent years, the number of call records has gone down but not gone away completely. In its last transparency report, the government said it collected 434 million phone records, down 18% on the year earlier.

But the government came under fire in June 2018 after it emerged the NSA had unlawfully collected 600 million call and text logs without the proper authority. The agency said “technical irregularities” meant it received call detail records it “was not authorized to receive.”

The agency deleted the entire batch of improperly collected records from its systems.

Following the incidents, the NSA reportedly shut down the phone records collection program citing overly burdensome legal requirements imposed on the agency. In January, the agency’s spokesperson said the NSA was “carefully evaluating all aspects” of the program and its future, amid rumors that the agency would not ask Congress to reauthorized its expiring Section 215 powers, set to expire later this year.

In an email Wednesday, the NSA spokesperson didn’t comment on the future of the program, saying only that it was “a deliberative interagency process that will be decided by the Administration.”

The government’s Section 215 powers are expected to be debated by Congress in the coming months.