Roma's long-delayed plans to build a new stadium hit another major obstacle Wednesday when nine people were arrested for alleged corruption linked to bureaucratic matters involving the venue.

Among those picked up by Carabinieri paramilitary police were the stadium's main constructor, Luca Parnassi, and six of his colleagues.

Prosecutors allege that payments were made illegally in cash, along with bills for non-existent job hires and counseling.

"Those that have erred will pay," Rome Mayor Virginia Raggi said. "We support legality."

A prosecutor announced that Roma was not involved in the investigation.

"We don't know anything about it," said Roma general director Mauro Baldissoni.

Roma's American president, James Pallotta, first presented the stadium plan in March 2014, saying that it would be ready for the 2016-17 season — yet construction has still not started.

The massive project — due to include a training center, entertainment complex, office space and extensive transportation works — has been delayed by environmental concerns, bureaucracy and criticism over public funding.

The project's cost was originally valued at 1.6 billion euros ($1.9 billion), including more than 200 million euros in public financing.

The proposed stadium site in Tor di Valle is about halfway between downtown and Leonardo Da Vinci Airport.

With a design inspired by the Colosseum, the stadium is slated to seat 52,500 and be expandable to 60,000 for major matches.

Roma currently shares the 72,000-seat Stadio Olimpico with city rival Lazio.