Ukrainian boxer Usyk detained at Krakow airport.

Editor's Note: This is a developing story and is being updated. 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.

Usyk's wife, Kateryna Usyk, 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 has 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.

Usyk says he has no interest in entering politics

"I won't leave boxing - it will always be with me.

I will work in boxing, I will help boxing.

It's a part of my life," Usyk said.