The highly rated footballer was followed by a number of Italy’s top clubs, but the Nerazzurri have been the most concrete of all the interested sides.
Inter official Marco Branca had a meeting in Sardinia with the player and his representatives yesterday with a view of luring Nainggolan to Giuseppe Meazza.
The mere fact Cagliari president Massimo Cellino gave the player permission to speak to Inter means he is close to reaching an agreement with the Nerazzurri.
Talented forward Samuele Longo is likely to move in the opposite direction as part of the deal, with Inter not prepared to pay the transfer fee in cash alone.
Radja Nainggolan, 25, has spent last three and a half years at Cagliari, making a total of 114 Serie A appearances and scoring 5 goals in the process.