Nainggolan, 30, joined Inter in August amidst major fanfare, despite his checkered history with domestic rivals AS Roma, with whom he faced internal disciplinary matters over his unprofessional conduct.
The controversial footballer was dropped by his former side in January this year after he posted a video of himself drinking and smoking while celebrating New Year's Eve, for which he subsequently apologised.
However, in the latest course of events, Inter have offered no explanation to his retrospective 'suspension'.
"FC Internazionale Milano can confirm that Radja Nainggolan has been temporarily suspended from football activity for disciplinary reasons," read the abrupt statement on the club's official website.
Nainggolan joined Inter in the for a reported £34m, shortly after being snubbed for the 2018 FIFA World Cup squad his Belgium, the nation he's since retired from representing.