The man, using the name Uri Brodsky, is suspected of working for Mossad in Germany and helping to issue a fake German passport to a member of the Mossad operation that allegedly killed Hamas agent Mahmoud al-Mabhouh in Dubai in January, a spokesman for the German federal prosecutor's office told The Associated Press.
Brodsky was arrested in early June upon his arrival in Poland because of a European arrest warrant issued by Germany which is now seeking his extradition, the spokesman said, declining to be named in line with department policy.
The spokesman had no estimate of how long it could take for Brodsky to be extradited from Poland to Germany, saying "the matter is now in the hands of the Polish authorities." If Brodsky agrees, the extradition could take a few days, but that isn't likely, the spokesman said.
In Warsaw, Monika Lewandowska, a spokeswoman for Polish prosecutors, confirmed that the suspect, identified only as Uri B., was arrested at the city's international airport on June 4. She told the AP that the arrest warrant was made "in connection with the murder of a Hamas member in Dubai."
The suspect appeared before a Polish court on June 6, and was ordered to remain in temporary arrest for up to 40 days, she said. Lewandowska had no information on his possible extradition.
In Israel, the Foreign Ministry said without elaborating that it was aware of the man's fate. "At the moment, we're looking into that like any other Israeli who has been arrested, and he's getting consular treatment," spokesman Andy David said.
Police in the United Arab Emirates said the elaborate hit squad linked to the Jan. 19 slaying in Dubai of al-Mabhouh - one of the founders of Hamas' military wing - involved some 25 suspects, most of them carrying fake passports from European nations.
Dubai's police chief, Lt. Gen. Dahi Khalfan Tamim, has said he is nearly "100 percent" certain that Mossad, Israel's spy agency, masterminded the killing.
The brazen assault in a luxury hotel and its alleged perpetrators were widely captured by security cameras. Some footage, released by Dubai's police, showed alleged members of the hit squad disguised as tourists, wearing baggy shorts, sneakers and baseball caps, and carrying tennis rackets.
At the time, Israel said it didn't know who was responsible for the killing but welcomed it, claiming al-Mabhouh was a key link in smuggling weapons to Gaza and a possible middleman with Israel's archenemy, Iran.
For Israel, the news about Brodsky's arrest comes at an already difficult time as the country is facing international criticism over its May 31 military raid on a humanitarian flotilla bound for Hamas-ruled Gaza that killed nine people.
The German news weekly Der Spiegel reported that the arrest in Poland already has already led to some diplomatic friction. The Israeli Embassy has urged Polish authorities not to extradite Brodsky, the magazine reports in its issue to be published Monday.
Germany's Foreign Ministry had no comment on the case and referred to an ongoing judicial investigation by the federal prosecutor's office. The country's top investigating unit deals with all cases affecting internal or external security, including terrorism or espionage.
After a German passport was used by a person linked to the Dubai slaying, the prosecutor's office in February started investigating a possible connection to a foreign intelligence agency.
Authorities in the western city of Cologne had issued a passport to a man named Michael Bodenheimer. A man using that name was among the assassins who killed the Hamas operative, according to Dubai police.
In February, German Foreign Minister Guido Westerwelle urged a thorough investigation and said German authorities would do everything possible to support their counterparts in the UAE.
If Brodsky's extradition goes through, however, it could put the government in Berlin - a staunch Israeli ally - in a difficult diplomatic position.