Poland on Monday announced plans for a barbed-wire fence along its border with Belarus following an influx of migrants which countries in the region called a "hybrid attack" on the EU.
Defence Minister Mariusz Blaszczak said the fence would be 2.5 metres (8.2 feet) high and would resemble the one built by Hungary along its border with Serbia.
"The work will begin next week," Blaszczak said, adding that it would be built along 130 kilometres of the border -- or around a third of the total distance.
Hungary built a fence along the Serbian border in 2015 and 2016 as Europe grappled with a large increase in migration from Syria.
Blaszczak also said the contingent of Polish soldiers currently deployed to help border guards would be doubled to 2,000.
"We will oppose the opening of a new route for the trafficking of migrants through Polish territory," the minister said.
Thousands of migrants -- mostly from the Middle East -- have crossed the EU border from Belarus in recent months and Brussels believes the influx is being deliberately engineered by the regime in Minsk in retaliation against EU sanctions.
Poland and the three Baltic states of Estonia, Latvia and Lithuania earlier on Monday urged the United Nations to take action against Belarus.
The four prime ministers said in a joint statement that the influx had been "planned and systematically organised by the regime of (Belarusian President) Alexander Lukashenko".
"It is high time to bring the issue of abusing migrants on the Belarusian territory to the attention of the UN, including the United Nations Security Council," the statement said.
"We urge the UN High Commissioner for Refugees to take active steps to facilitate the solution of this situation," it said.
The three EU countries that share a land border with Belarus -- Latvia, Lithuania and Poland -- are all trying to block or push back migrants who attempt illegal crossings.
In many cases, Belarusian authorities reportedly push the migrants back towards the EU border -- which Lukashenko has denied -- leading to several stand-offs.
One such stand-off forced a group of Afghan migrants onto a section of the Poland-Belarus border, where they have been stranded for two weeks at a makeshift encampment.
Polish human rights organisations and the liberal opposition have accused the populist right-wing government of refusing to help people in need and violating international rules.