Five Polish soldiers were killed in Afghanistan in what was the single biggest attack on Polish forces since their deployment in the country, Polish media reported.
A spokesman for the governor of Ghazni province said the soldiers were killed by a mine. Ghazni province lies southwest of the Afghan capital.
It was one of "the most tragic events" in the country's mission so far, Polish Prime Minister Donald Tusk said.
The Taliban claimed responsibility for the Ghazni attack in a text message sent to journalists.
Poland has about 2,500 soldiers in Afghanistan as part of the US-led mission, which it joined in 2002.
The latest attack raised Poland's overall death toll in Afghanistan to 36.