Martinez has played a key role in his side winning the 2020-21 Serie A title, scoring 16 goals and registering nine assists in 37 appearances.
The 23-year-old had been expected to sign a new contract with Inter earlier this year, but there has still not been an official announcement, and the speculation surrounding his future has surfaced once again.
Barcelona have previously been linked with the Argentina international, but according to Marca, Martinez's agent Alejandro Camano has met with senior figures at both Real Madrid and Atletico to discuss a potential move to La Liga.
The report claims that Inter's financial problems could lead to the Italian champions sanctioning the sale of the centre-forward during this summer's transfer window.
Chelsea, Manchester City and Liverpool are also all believed to be keeping a close eye on the developments surrounding the South American.