Poland's prime minister calls weekend rail line explosion near Warsaw act of 'sabotage'

Meanwhile, Poland's defence chief Władysław Kosiniak-Kamysz said that the army would examine 120 kilometres of the Warsaw-Lublin-Hrubieszów line, which links the capital to Ukraine by rail and road.

A railway line linking Warsaw to southeastern Poland was damaged by a weekend explosion that Prime Minister Donald Tusk called an "unprecedented act of sabotage".

Tusk, who visited the site on Monday, said the line is "crucially important for delivering aid to Ukraine."

"Unfortunately, the worst fears have been confirmed," the Polish leader said in a statement Monday.

"An act of sabotage has occurred on the Warsaw-Lublin route. An explosion has destroyed the railway track."