Two-time European champion Porto was fined 1.5 million euros ($1.6 million) by UEFA on Friday and threatened with a one-year ban from European competitions because of unpaid debts this season.

UEFA said its club finance monitoring panel put Porto on probation for two years and the ban will be imposed "if the club does not fulfill the solvency requirements” in the next two seasons.

The threat has been inherited by new club president André Villas-Boas, its one-time coach who went on to work at Chelsea and Tottenham. Villas-Boas last month ended the 42-year presidency of Jorge Nuno Pinto da Costa.

Two clubs — Shakhtyor of Belarus and Adana Demirspor of Turkey — were banned for one season for failing to comply with UEFA financial rules. Those bans will be enforced the next time either qualifies for a UEFA competition through the 2026-27 season.

Shakhtyor, which has been implicated in match-fixing in Belarus and hit with points deductions in the national league, was fined its 1.01 million euros ($1.1 million) of UEFA prize money for playing in recent European competitions.

The UEFA panel analyzes the accounts of hundreds of clubs which qualify for its European competitions in a financial monitoring system once known as “Financial Fair Play.” The first sanctions in 2014 included 20 million euros ($21.7 million) payments by Manchester City and Paris Saint-Germain.

Porto was the headline case of 13 clubs sanctioned by the UEFA panel for so-called “overdue payables” — unpaid or late-paid debts for wages, transfer fees to other clubs or social taxes.

Porto has earned about 60 million euros ($65 million) from UEFA in each of this season and last season for reaching the round of 16 in the Champions League. However, the team has qualified only for the second-tier Europa League next season.

Turkish league leader Galatasaray and Real Betis of Spain also were fined by UEFA though each must pay just 30,000 euros ($32,600).

CSKA Sofia was fined 450,000 euros ($490,000) and Vitória of Portugal, which is part-owned by Aston Villa’s owners, was ordered to pay UEFA 200,000 euros ($217,000). Both CSKA and Vitória were put on probation with the threat of one-season bans by UEFA.