A call by German Chancellor Olaf Scholz for Warsaw to clarify allegations surrounding migrant visas is an attempt to interfere in the Polish election campaign, Poland's Foreign Minister Zbigniew Rau said.
Migration has emerged as a main campaign theme ahead of the closely-contested on 15 October elections.
The government has faced accusations by opposition parties this month that it was complicit in a system in which migrants received Polish visas at an accelerated pace without proper checks after paying intermediaries.
On Saturday, German Chancellor Scholz said the issue required clarification and suggested that Germany may take steps related to checks on the border with Poland.
"The competence of the German Chancellor clearly does not concern the ongoing proceedings in Poland," foreign minister Rau wrote on X social media platform late on Sunday.
"Statements in this regard indicate an attempt to interfere in the internal affairs of the Polish State and the ongoing electoral campaign in Poland," he said.
Rau appealed to the German Chancellor to "respect Poland's sovereignty and refrain from statements that damage our mutual relations."
Earlier, EU Commissioner for Home Affairs Ylva Johansson demanded clarification on the matter and called on Poland to respond to allegations that as many as 350,000 migrants purchased EU Schengen visas in Polish consulates through intermediaries.
Schengen visas often allow holders to travel elsewhere in the EU.
In a letter to the EU's security commissioner, Poland's government said the affair was an exaggerated "media fact" timed to discredit it ahead of the election.