Portsmouth's new owners Convers Sports Initiatives have admitted they were surprised by the lack of investment made by the club's previous owners.
Vladimir Antonov and Roman Dubov, who took over at Fratton Park in June, also promised to improve infrastructure at the Championship club.
"In the past six-or-seven years around half-a-billion pounds was moving around the club," Dubov told BBC South Today.
"But we don't even have proper toilets in the stadium... this was a nonsense."
The Russian continued: "What we can promise is that that will not happen with us."
He added: "We want to see a proper football club with a business structure inside. In all aspects of the club, from the commercial side to the academy, they are not in good shape. Only if we improve all these points will the club be successful."
Portsmouth were the first ever Premier League club to enter administration in February 2010, and despite a host of high-profile signings and reaching an FA Cup final, fell from the top-flight into the Championship last year.
CSI took over from Sports Holdings (Asia) Ltd, but Dubov said the new owners would not try to buy their way back to the top-flight, and would instead focus on a longer-term plan which would include bolstering the club's academy system.
"We're not planning to invest huge money into the squad," he explained. "If you put a new engine from a Ferrari into a Mini it will not bear [it]. But we will put money into the academy and we want to improve the facilities, our training ground - we want to be a proper football club."
Antonov continued: "We decided we'll be long-term investors, we don't want to sell the club - we have a five-year development plan. For us it's a long term investment and a passion, emotionally we're very addicted to Portsmouth Football Club."
He added: "Our main goal is to give supporters confidence that we are stable owners and that we have the passion and money to support the club's long-term vision."
The duo, who own CSI with former Leeds United chief executive Chris Akers, have sporting interests in Lithuania and Russia, and are also involved in the World Rally Championship, PowerPlay Golf, the Spartak Moscow ice hockey team and the Isle of Man TT motorcycle race.
The pair also committed to resolve issues over Fratton Park's redevelopment, which have been complicated because land around the club is owned by former owner Alexandre Gaydamak.
"Currently we're working on how to expand our territory around Fratton Park," Antonov said. "We'll do our best to buy this plot of land back to the club again."
Dubov added: "[The ground] is a priority for us, right now we're doing some investigation and working with the lawyers, we're working on it."
The CSI owners, who were behind a failed bid to buy Bournemouth in 2010, also explained how they ended up investing in Pompey.
"When we decided to buy a football club we started our research around the south of England," Anotnov said. "We started from League Two, then League One, and then we found Portsmouth.
"And we found a fantastic club, with a fantastic spirit, and history and heritage and an army of supporters with huge potential for the future.
"We want to develop the club, it's not a toy, it's not just one of our assests - we're becoming addicted and we will continue with that."