Polish soldiers were building a fence on the border with Belarus on Thursday, as the European Union's largest eastern member takes steps to curb illegal border crossings despite criticism that some migrants are being treated inhumanely.
Brussels has accused Belarusian President Alexander Lukashenko of using migrants as part of a "hybrid war" designed to put pressure on the bloc over sanctions it has imposed, and building the wall is part of Poland's efforts to beef up border security on the EU's eastern flank.
"Almost 3 km of fencing has been erected since yesterday," Defence Minister Mariusz Blaszczak said on Twitter, adding that almost 1,800 soldiers were supporting the border guard.
On Thursday Reuters saw soldiers next the frontier stringing wire through barbed wire to hook it to posts.