The agent of Keita Balde Diao claims that both Liverpool and Juventus failed in their attempts to sign the Lazio striker.
Reports over the summer suggested a fee of around £24million would be required to secure the 19-year-old's services, but agent Anglo Cascella says both clubs made offers closer to £16million which were turned down.
Keita established himself as a regular with Lazio last season, making 33 appearances all competitions and finding the net on six occasions.
Cascella told Efe: "Liverpool and Juventus offered a sum of 20 million euros for Keita last summer, but Lazio always rejected their offers.
The former Barcelona academy product is currently awaiting clearance to represent Spain at international level, but has had problems due to his Senegalese heritage.
"Keita is really disappointed because he sees himself as Spanish and he doesn't understand these delay," said Cascella.
"He's frustrated not to be able to defend the colours of his country."