The businessman is regarded as one of the most influential figures in Latvian politics.
One of the most influential figures in Latvian politics has been sentenced to five years in prison for corruption.
Aivars Lembergs, the mayor of the city of Ventspils since 1988, was convicted by a court in Riga on Monday of bribery and money laundering.
The wealthy businessman was immediately arrested after the sentence and fined an additional €20,000.
The court ruled that he must pay damages against several individuals and former business rivals, and confiscated a number of Lembergs' assets, which are believed to amount to several million euros.
Property seized included offshore shell companies, shares, bank accounts, real estate, cars, jewellery and even a small trailer for his vehicle, the court said. The decision brings an end to the longest criminal trial in Latvia's recent history.
Lembergs - who denied the charges - intends to appeal the decision, describing the trial as a political reckoning.
The 67-year-old oligarch was first investigated by Latvian authorities in 2007 and was accused of more than 40 corruption offences.
Lembergs is considered one of the richest men in Latvia and repeatedly stood as a candidate for Prime Minister as part of the Union of Greens and Farmers.
Many of his corrupt activities were said to have taken place during "transit wars" in the 1990s, where business rivals looked to trade with Russian oil and fertilisers through the country's second-largest port.
In 2019, the United States Treasury Department linked Lembergs "directly or indirectly" to bribery linked to public contracts and his private property, and imposed sanctions on the Ventspils port authority. He was found guilty of 19 of the total 40 charges on Monday.
Lembergs' son, Anrijs, and business partner, Ansis Sormulis, were also sentenced to two years in prison and had their assets confiscated, for being accessories to racketeering and for laundering illegally obtained money.