Anti-racism groups on Friday called on European football's governing body UEFA to punish Polish club Legia Warsaw after fans brandished a "Jihad" banner during a Europa League match against Israeli side Hapoel Tel Aviv.
"This is yet another case of anti-Semitic behaviour by extremist groups active in Polish football stadiums, and it could have been predicted," Rafal Pankowski of the campaign group Never Again and who runs the UEFA-backed Football Against Racism in Europe network.
At the start of Thursday night's Group C home game in Warsaw - which Legia won 3-2 - a group of fans unfurled a huge banner stretching across three blocks of a stand.
Written in Arabic-style letters, it read "Jihad Legia". The banner was green, which is one of Legia's colours but also that of Islamist groups.
Miroslaw Starczewski, deputy head of security at Poland's PZPN football association, said Legia could be hit hard by UEFA. "A fine is the most likely penalty. And UEFA may even ban Legia fans from the second leg in Tel Aviv (on December 15)."
Stadium racism and hooliganism are in sharp focus in Poland ahead of the 2012 Euro Championships, which the country will host along with neighbouring Ukraine.