Footage of the incident went viral online on Monday.
A separate review of the bus's surveillance recording showed the driver, on hearing screams, asking the passenger to stay calm – an attempt, according to transport operator MZK Bielsko-Biała, to draw his attention away from the girls.
'Haters will not go unpunished': interior minister
Interior Minister Marcin Kierwiński confirmed the man had been taken into custody, warning that "every form of aggression will meet a firm response from the state" and that "haters will not go unpunished."
Ukraine's Foreign Minister Andrii Sybiha thanked Polish law enforcement for their swift action, saying such hostility "cannot be tolerated in a European, democratic society or state."
He also reiterated calls for some Polish politicians to stop fomenting hatred towards Ukraine and Ukrainians.
MZK Bielsko-Biała said it would contact the girls, working with the city's mayor, to discuss support and possible redress.
Concerns over similar incidents
The incident is the latest in a series of anti-Ukrainian episodes in Poland.
Last week, two men were detained after demanding entry to a Ukrainian-owned business to check whether its owner "supports Stepan Bandera" – a Ukrainian nationalist leader who fought for Ukrainian independence during and after World War II, and remains a divisive figure.
A caption accompanying footage of the encounter, shared online, described the pair as activists supporting far-right politicians Grzegorz Braun and Korwin-Mikke.
In late June, a resident of Gliwice attacked a 46-year-old Ukrainian man with a baseball bat, injuring him.
Police said the attacker had first behaved aggressively and hurled nationality-based insults at a group of Poles and Ukrainians at a gathering.
A study by the Res Futura think tank of nearly 520,000 social media posts from May found anti-Ukrainian sentiment increasingly widespread online, with pro-Ukrainian posts now making up roughly one in a thousand.
(ał)
Source: PAP