Ukrainian boxer Oleksandr Usyk was arrested at the airport in Krakow, Poland, Ukrainian lawmaker Zhan Beleniuk said on Sept. 17.
"Oleksandr Usyk was arrested at the Krakow airport. The circumstances are being investigated," Beleniuk said via Telegram.
Beleniuk also posted video of Usyk's arrest.
President Volodymyr Zelensky announced shortly after midnight on Sept. 18 that Usyk had been released following the intervention of Ukraine's Foreign Ministry. He also said he spoke to Usyk by phone while he was detained.
"I was outraged by this treatment of our citizen and champion," Zelensky said.
The arrest resulted from "a misunderstanding," Usyk wrote in an Instagram post after his release.
"There was a misunderstanding that was quickly resolved," he said.
"Thank you to everyone who was worried. I thank Ukrainian diplomats for their support. And respect to the Polish law enforcement officers who perform their duties despite their height, weight, arm span, and regalia."
Usyk's wife, Kateryna Usyk, earlier wrote on social media that the arrest was not related to anything criminal.
"Everything is fine, nothing criminal," she said.
On the instructions of Foreign Minister Andrii Sybiha, Ukraine's Consul General in Krakow went to the airport to intervene on Usyk's behalf, ministry spokesperson Heorhy Tykhyi said in a statement.
"The Ukrainian side categorically rejects the attitude to its citizen and champion demonstrated in the video," Tykhyi said.
Sybiha reportedly appealed to his Polish counterpart to resolve the situation.
Usyk became the undisputed heavyweight world champion after defeating British boxer Tyson Fury back in May.