The Constitutional Court in Moldova has ordered the immediate dissolution of pro-Russian party Sor.
The court said that the party was "unconstitutional" and would be banned.
In March, Moldova's police chief warned that Russian intelligence agencies had been using protests organised by Sor to try to destabilise the country.
The Sor party is led by Ilan Shor, a fugitive businessman who fled to Israel since 2019 after being convicted of fraud and money-laundering.
Following the court ruling, Shor took to Facebook to claim that the move had "nothing to do with a rule-of-law state, democratic principles and values, the supremacy of laws and the constitution".
He also said that the decision was made under pressure from "puppeteers from abroad".
Shor pledged to appeal against the ruling at the European Court of Human Rights and "to bring to account all those who participated in this illegal process".
Supporters of the party gathered outside the Constitutional Court in Moldova's capital, Chisinau, ahead of the ruling, carrying signs with anti-government slogans.
Moldova's pro-Western president, Maia Sandu, welcomed the court's decision, writing on Facebook that it was "expected by society because Moldovans value democracy and want to live in a democratic state which respects the rule of law, a state where criminal organisations are not protected but prevented from capturing the state".
Ms Sandu said that the Sor party was "set up because of corruption and for corruption" and that it "poses a threat to the constitutional order and the state's security".
Last February, Sor organised demonstrations in Chisinau and reportedly paid for protesters from across the country to attend them.
At the time, Ms Sandu accused Russia of plotting to use foreign "saboteurs" to overthrow her pro-EU government with the aid of foreign saboteurs from Russia, Serbia, Belarus and Montenegro.
Shor is now under UK, US and EU sanctions for working in collusion with Russia to try to destabilise Moldova and topple its government.
When he fled Moldova, he was facing prosecution for involvement in the theft of $1bn from three Moldovan banks for which he was sentenced to 15 years in prison. Moldova has repeatedly asked Israel to extradite Shor.
Following the Constitutional Court's ruling, Moldovan media reported that the five Sor party parliament members would "continue to exercise their mandates as independent deputies without the right to join any other parliamentary factions", stressing that the court's decision "is final and cannot be appealed".