An official at the office of prosecutor Antonio Salinas told the Associated Press that the probe into the alleged $50 billion fraud was launched at the end of last month.
Spanish daily El Pais said the case is currently focused on a Madrid-based partner in the investment firm Fairfield Greenwich, a US-based company that funneled investors to Mr Madoff's company, the news agency noted.
Authorities in Luxembourg, Germany, Austria, Ireland and France have so far launched inquiries in the Madoff affair, Bloomberg reports.
Britain's Serious Fraud Office is also conducting a probe into the scandal to determine if any crimes relating to the alleged fraud were committed in the UK.
Mr Madoff, who founded his investment firm in 1960, has been under investigation in the United States for securities fraud since his arrest on December 11th.