The migrant crisis at the EU border with Belarus has spread to more countries, with Latvia and Poland both alarmed by a surge of new arrivals.
Lithuania had previously taken the brunt of a migrant wave which Belarus is accused of masterminding to retaliate against EU sanctions.
A state of emergency took effect in neighbouring Latvia on Wednesday after more than 200 people arrived in 24 hours. The number detained at the border has risen more than fourfold since August 6.
Latvia’s move allows the police and military to support border guards and use force if necessary to order illegal migrants to leave.
“The emergency regime means that the border between Latvia and Belarus will be practically closed to everybody,” said Latvian Prime Minister Krisjanis Karins.
In Poland, which also shares a border with Belarus, authorities reported 349 migrants arriving since Friday.
Polish guards said they were thought to be from Iraq or Afghanistan and the numbers arriving were at a record high.
Guards on the Belarusian border have detained 871 illegal migrants this year, up from 122 last year.
In Lithuania, where more than 4,000 people have arrived this year, Parliament voted on Tuesday to approve the construction of a border fence.
At a cost of €152 million ($178m), the barrier will be topped with razor wire and cover more than 500 kilometres of Lithuania’s border with Belarus.
"We must have a strong and reliable border with Belarus ... as soon as possible," Interior Minister Agne Bilotaite said.
Lithuania’s Parliament also voted to allow the military to patrol alongside border guards and turn back people deemed to have crossed illegally.
Those wanting to claim asylum must now do so at an official border crossing or at an embassy.
The EU is accusing Belarus of ferrying migrants to the border to retaliate against Brussels and neighbouring countries who have sheltered opposition figures.
Lithuania is the adopted home of Belarusian opposition leader Sviatlana Tsikhanouskaya, who fled her home country last year.
Poland gave refuge to Belarusian sprinter Krystsina Tsimanouskaya after she refused to return home from the Tokyo Olympics.
Western governments hit Belarus with more sanctions this week on the first anniversary of an election which was widely regarded as rigged.
The election was followed by mass protests against President Alexander Lukashenko and arrests of opposition figures.
Relations with the EU soured further when Belarus forced a commercial jet to land in Minsk and arrested the dissident journalist Roman Protasevich who was on board.
The migrant crisis has escalated tension even further, with Brussels accusing Belarus of cynically exploiting the hopes of Iraqis.
After discussions with Iraq, the EU said there had been a significant decrease in crossings after Baghdad suspended flights to Belarus.
EU ministers are to discuss the issue at a crisis meeting next week.