A Ugandan human rights lawyer who represents opposition figure Bobi Wine was arrested on Tuesday on charges of money laundering, police said.
Nicholas Opiyo is the founder of the robust human rights defence organisation Chapter Four Uganda and is the lawyer for many activists.
Rights groups have increasingly criticised Uganda over arresting political opponents and violating freedom of association, assembly, and expression as last year authorities introduced new regulations restricting online activities and stifling independent media.
Uganda Police Force confirmed Opiyo's arrest on Twitter for "allegations of money laundering and related malicious acts".
"The investigations are progressing well and any new developments will be communicated in due course," it added.
Opiyo is detained at the Special Investigations Division. He was arrested with three other lawyers; Herbert Dakasi, Anthony Odur and Esomu Obure.
In a statement, Chapter Four Uganda said it is "deeply concerned about the abduction and incommunicado detention" of Opiyo.
Amnesty International's Eastern African bureau also condemned the "arbitrary arrest" and called for the lawyers' release.
According to Bobi Wine, Opiyo was arrested along with three other lawyers and a member of his party.
Wine, a former pop star turned politician, has emerged as the strongest challenger to Uganda’s longtime leader Yoweri Museveni in elections set for early next year. Museveni is seeking a sixth term.
Wine was arrested on November 20 and later released on bail, sparking violent clashes between his supporters and security forces, which killed 37 people.
It was unclear who was responsible for the deaths. Most of the dead suffered gunshot wounds and traumatic injuries, Ugandan police said.
Opiyo said at the time Wine was arrested on a coronavirus violation. But, he said, “the actual reason really is that it is part of the broader attempt to stifle opposition campaigns."