Migrants heading for Poland are receiving text messages telling them the border is closed and to “go back to Minsk” where Belarusian authorities are allegedly egging them on.
The texts from the Polish government tell migrants they were lied to by Belarusian officials and sow fears they could be poisoned.
The messages are being sent to foreign phones in a border area that is under a state of emergency amid a rush of people from Belarus.
Belarus is accused by European leaders of ferrying migrants to the border in a pressure campaign against EU sanctions. Lithuania and Latvia are also affected.
Nearly 31,000 phones in the border area had received the text as of Wednesday morning, said Polish Interior Minister Mariusz Kaminski.
“The Polish border is sealed. BLR authorities told you lies,” the message reads in English, using an abbreviation for Belarus.
“Go back to Minsk! Don’t take any pills from Belarusian soldiers,” it says.
The reference to pills comes after reports migrants were given tablets by Belarusian police before heading for the Polish border.
The text message links to a government website that issues an explicit warning that migrants could be poisoned.
It tells migrants the border is heavily guarded and they could go to prison if they cross illegally.
“Crossing the Polish border will not help you reach Germany,” migrants are told. “Worsening weather conditions may be dangerous to life and health."
Aid groups have criticised Poland for its treatment of the migrants, many of whom came from Iraq.
The state of emergency, which officials want to extend for 60 days, means authorities can shut human rights groups out of the border area.
Amnesty International published findings on Thursday, based on satellite imagery and other photos, which allegedly showed Poland forcing people back over the border to Belarus.
It said 32 Afghan asylum seekers had surfaced on the Belarusian side of the border after apparently being surrounded by Polish border guards.
“The dire situation facing the Afghans on the border is one that the Polish government has created,” said Eve Geddie, Amnesty’s top advocate to the EU.
“The EU must act swiftly and firmly to call out these flagrant abuses of EU and international law.”
The European Commission last week voiced concern about the migrants’ plight and urged Poland to allow EU border guards to provide assistance.
But EU officials are also ramping up pressure on Belarus by placing visa restrictions on members of President Alexander Lukashenko’s government.
Under proposals made on Wednesday, Brussels would water down a visa agreement that makes it easier and cheaper to get an entry permit from Belarus.
The tougher rules would apply to official delegations from Belarus rather than the general population.
Ylva Johansson, the EU’s Home Affairs Commissioner, said Mr Lukashenko was trying to make money from migrants desperate to reach Europe.
“He is trying to destabilise the European Union by bringing in migrants, and facilitating them, and pushing them into the European Union,” she said.
“He is actually deceiving people to pay a lot of money just to be trapped and tricked.”