Polish border guards have stopped a refrigerated lorry carrying 34 migrants on the motorway heading towards Germany.
The truck, bearing Lithuanian number plates, was travelling on the A2 motorway near Poznań, a spokeswoman for the border guard agency told the PAP news agency on Tuesday.
During the inspection, it emerged that people were hidden in the refrigerated compartment behind a specially fitted partition. They came from several different countries, including Pakistan, Egypt, Somalia and Sudan.
"The foreign nationals had documents proving that they had applied for international protection while on Latvian territory," said the Border Guard spokeswoman.
They were handed over to the authorities of Poland's neighbour, Lithuania, as part of the repatriation process. The lorry driver is under investigation.
Poland and the Baltic States accuse the Belarusian leader Alexander Lukashenko of systematically transporting migrants from crisis-hit regions to the EU's external border to exert pressure on the West.
Poland has now secured its border with Belarus with a five-metre-high fence and electronic surveillance cameras.
On Latvia's similarly secured border with Belarus, tunnels were discovered on several occasions in August through which migrants were able to enter the EU country illegally.