Polish contractors have begun work on a $407-million (€353-million) wall along the Belarus border aimed at deterring migrant crossings following a crisis in the area last year.
The 5.5-metre high wall will run along 186 kilometres of the border – almost half the total length – and is to be completed in June, according to Krystyna Jakimik-Jarosz, a border guard spokeswoman.
"As planned, the construction sites were turned over to the contractors on Tuesday," said Jakimik-Jarosz.
She refused to reveal the exact locations "for security reasons" but said the wall would be equipped with cameras and motion detectors.
Previously, Poland also built a razor wire fence along much of the border and closed off the frontier area to media and human rights groups.
Jakimik-Jarosz said the razor wire fence had helped the border guards.
"It bought us time to prepare when a group of migrants were getting ready to attack, to create an opening. We had the time to mobilise the means and personnel required to stop them," she said.
Poland has also approved a new law allowing migrants to be forced back into Belarus.
Human rights concerns
The construction has raised human rights concerns over how migrants will be able to seek asylum as well as environmental worries about the effect on wildlife along the mostly forested border.
Thousands of migrants – mostly from the Middle East – crossed or attempted to cross the border from Belarus into Poland last year.
The West blamed the influx on the Belarusian regime, saying it had encouraged would-be migrants to fly to Belarus with the promise of an easy journey on foot into the European Union.
While the number of crossings has fallen sharply since then, some still attempt the increasingly perilous crossing despite the freezing conditions.
The border guard service said on Twitter on Tuesday that there were 17 crossings in the past 24 hours.
A group of 14 people – 11 Iranians, two Lebanese and one Syrian – "cut the razor wire fence and crossed into Poland", border guards said.
They were detained, along with a separate group of three people from Ghana who crossed over a different part of the border.