Poland's coastguard have fired warning shots at a German ship as it fled Polish waters after undercover customs inspectors tried to question the captain on his journey, Polish officials said on Thursday.
No one was hurt in the incident and the German passenger ship, Adler Dania, returned safely to port in Heringsdorf, Germany. But the incident has inflamed already strained German-Polish relations.
The German captain, Heinz Arendt, said he turned his ship around after "what were apparently Polish customs officials" took him by surprise when they came on board after the ship docked in the Polish port of Swinoujscie on Tuesday.
The German ship headed out to sea with the Polish customs officials still on board.
German media quoted crew members as saying they believed Polish coastguard had then fired at them with machine guns and rifles. Arendt said three or four shots were fired at the ship. But Polish customs officials said the coastguard had merely fired blanks.
They said Arendt disobeyed radio calls from Poland's coastguard ordering him to stop his ship and that they were pressing kidnapping charges with Polish prosecutors against him.
"We have the right to stop German ships in Polish waters just like Polish police have the right to stop German cars on Polish roads," said Janusz Wilczynski, spokesman for Polish customs in the Baltic port city Szczecin.
The German Foreign Ministry had no immediate comment while the Polish Foreign Ministry said the incident should have no impact on ties between the two neighbours.
"We don't intend to let this incident have any influence on German-Polish relations," ministry spokesman Tomasz Szeratics said. "We are not taking any official steps."
Wilczynski said undercover customs agents boarded the Adler Dania at Swinoujscie to check whether the ship was selling cigarettes and alcohol without paying excise tax, which is punishable in Poland by a hefty fine.
They approached the captain to question him, at which point he turned the ship around and returned to German waters. Poland's coastguard briefly gave chase.
German police detained and questioned the Polish customs officers once the ship returned to Heringsdorf, five km (3 miles) west of the Polish border. They were later released.
Arendt said he notified his company when he detained the Polish officials after they asked to get into the bulkhead.
"The question was: Where did these Polish customs officials come from? The identity was not clear because the boat had just come over from Germany," he said. "So I detained them and told them I was going to turn them over to German authorities and clear that all up after we returned to port.
"As the captain, I'm entitled to ensure the security of the boat and its passengers -- even abroad," he added.
A spokesman for the company that owns the ship said the captain was within his rights to flee Polish waters because the agents lacked a search warrant and international passports.