(Bloomberg) -- German Chancellor Olaf Scholz called on Poland to investigate reports that officials issued hundreds of thousands of illegal work visas and threatened to restore controls at the Polish border.

“I don’t want Poland just to wave through” migrants, Scholz said at a Social Democratic campaign event in Nuremberg. “Depending on the situation, we may have to take additional measures at our borders, for instance at that one.”

Germany’s warning raises the prospect of disruptions at a border between two European Union economies and adds to friction with the government in Warsaw as Poland heads toward a parliamentary election on Oct. 15. Both countries are members of Europe’s visa-free travel agreement that’s meant to smooth travel and trade.

Scholz and Faeser have previously resisted calls to introduce border controls and the comments signal increasing pressure on Germany’s government to respond to rising numbers of undocumented arrivals.

Polish media have reported that bribes were involved in allowing more than 250,000 citizens of African and Asian countries to work in Poland over the past two-and-a-half years.  The Foreign Ministry in Warsaw disputed the number and said it’s investigating only 268 visa requests. EU Home Affairs Commissioners Ylva Johansson has asked Poland to provide “clarifications” by Oct. 3.

More than 204,000 people requested asylum in Germany through August, a 77% increase compared to the same period last year, according to government data. More than 12,000 undocumented migrants were taken into custody at the Polish border in the first half of this year, according to German police.

Poland’s right-wing government has long criticized Germany’s liberal immigration approach and has rejected an EU-wide refugee policy. Scholz was in Nuremberg to campaign for his party ahead of a state election in Bavaria, where the governing conservative Christian Social Union holds a wide lead in polls ahead of the Oct. 8 vote.    

(Updates with Scholz quote in second paragraph.)

©2023 Bloomberg L.P.