ESPN could not determine if the system was ever used. The report on Monday's "Outside the Lines" said Loomis would have been able to eavesdrop on opponents from 2002 to 2004. The report also said the system was disabled in 2005, when the Superdome was heavily damaged by Hurricane Katrina.
Saints spokesman Greg Bensel called the report "1000 percent false."
"We asked ESPN to provide us evidence to support their allegations and they refused," Bensel said. "The team and Mickey are seeking all legal recourse regarding these false allegations."
If the Saints had installed a system allowing them to listen in on their opponents it would have violated NFL rules and also could have infringed on federal wire-tapping laws.
"We were not aware of it," league spokesman Greg Aiello said. "We have no knowledge of the allegations."
FBI spokeswoman Sheila Thorne said the agency's New Orleans office was aware of the situation, but wouldn't comment further.
U.S. Attorney Jim Letten in New Orleans also said his office had been told about "general allegations" involving the Saints and possible wiretapping, but he did not elaborate. Letten declined to discuss who made the allegations, and whether they involved Loomis or any other Saints officials.
For the Saints, the report in itself added to a slew of recent bad publicity, which began in early March when the NFL released a report describing a crunch-for-cash bounty system that provided improper cash bonuses to defensive players who delivered hits that hobbled targeted opponents.
Commissioner Roger Goodell has suspended head coach Sean Payton for the entire 2012 season in connection with the bounty probe. Loomis, who did not comment directly on the latest report, was suspended for the first half of the regular season and assistant head coach Joe Vitt was suspended six games.
The team also lost its second-round pick in this week's NFL draft and was fined $500,000. Goodell took away the Saints' second-round pick in 2013 as well, but has said he may lessen that punishment if he is satisfied with the club's cooperation in the ongoing investigation.
The NFL still has yet to hand down punishment to between 22 and 27 current and former Saints defensive players whom the league has said participated in the bounty program.