Congress is demanding answers from the Biden administration about a secret spying program that tracks more than a trillion phone records from innocent and unsuspecting Americans each year.

The under-the-radar system, known as Data Analytical Services or 'Hemisphere,' has been in operation for over a decade. It allows federal, state, and local law enforcement agencies to tap into the phone records of U.S. citizens who have not been accused of any crime.

Under the Hemisphere program the White House Office of National Drug Control Policy (ONDCP) pays phone service provider AT&T to hand over phone records as far back as 1987.

The deal first came to light in 2013 after a bombshell New York Times report, but it has since been expanded.

Sen. Ron Wyden, D-Ore., has now written to the Department of Justice (DOJ) demanding documents related to the Hemisphere program be made public and raising 'serious concerns' about its legality.

According to the letter, Wyden received 'sensitive' information about the program from the DOJ - allowing him to view it but not share it with the wider public.

The senator said the 'troubling information' he'd learned about the program 'would justifiably outrage many Americans and other members of Congress.'

Republican congressman Andy Biggs, Ariz., accused the government of spying on Americans.

Hemisphere is 'invasive' and allows 'government agents warrantless access to trillions of Americans' domestic communications records,' he said.