Two-time European champions Porto were fined 1.5 million euros by UEFA on Friday and threatened with a one-year ban from European competition for unpaid debts this season.

UEFA said that as part of its Financial Fair Play and financial monitoring of clubs, Porto had been placed on probation for two years and the ban would be imposed "if the club fails to meet the solvency requirements" in the next two seasons.

The northern Portuguese giants have won a total of seven official international titles, including two Champions Leagues (1987, as European Cup, and 2004), two UEFA Europa Leagues (2003, as UEFA Cup, and 2011), one Super Cup (1987) and two Intercontinental Cups (1987 and 2004).

That threat has been inherited by the club's new president, André Villas-Boas, the former coach of English giants Chelsea and Tottenham. Last month, Villas-Boas ended Jorge Nuno Pinto da Costa's 42-year presidency at Porto.

Porto have earned around 60 million euros ($65 million) from UEFA this season and last season by reaching the last 16 of the Champions League. However, they have only qualified for next season's second-tier Europa League.

In addition to the Portuguese club, Belarus' Shakhtar and Turkey's Adana Demirspor have also been handed one-year bans for failing to comply with UEFA's financial regulations. The bans will take effect the next time either club qualifies for a UEFA competition until the 2026-27 season.

The Belarusian club has been involved in match-fixing in its country and has been sanctioned with a deduction of points from its domestic league. It has also been fined $1.1 million in UEFA prize money for its participation in recent European competitions.

UEFA's committee examines the accounts of hundreds of clubs that qualify for its European competitions under a financial monitoring system formerly known as Financial Fair Play. The first sanctions, imposed in 2014, included payments of $21.7 million by elite clubs such as Manchester City and Paris Saint-Germain.

Turkish league leaders Galatasaray of Istanbul and Real Betis of Seville (Spain) were also fined by UEFA, although they only had to pay $32,600 each.

CSKA Sofia of Bulgaria were fined $490,000, while Vitória of Portugal, partly owned by the owners of Aston Villa, were ordered to pay UEFA $217,000. Both CSKA and Vitória were placed on probation with the threat of a one-season ban by UEFA, which is taking an increasingly tough stance on financial fair play enforcement.