Polish medics attend an intervention as Polish border guards stop another group of migrants from crossing the border from Belarus.
Polish police have clashed with migrants trying to cross the border from Belarus.
Thousands of migrants gathered near the Belarus border on Monday, Polish authorities said, as European Union member states called for more sanctions against Minsk and security forces braced for more attempts to force through the frontier.
Warsaw has accused Belarus of trying to spark a major confrontation, with video clips showing hundreds of migrants walking towards the Polish border and some trying to breach the fence using spades and other implements.
"We expect that in the coming hours attacks on our border will be renewed by groups of several hundred people," Pawel Soloch, the head of Poland's National Security Bureau, told reporters.
Polish government spokesman Piotr Muller said that there were currently 3,000-4,000 migrants near the border, and more than 10,000 others across Belarus ready to try and cross into Poland.
Warsaw said it had deployed additional soldiers, border guards and police, while neighbouring Lithuania said it might introduce a state of emergency on its border with Belarus.
Poland said it had withstood the first attempts on Monday by the migrants to force their way across the border.
The Sun newspaper brings you the latest breaking news videos and explainers from the UK and around the world
Become a Sun Subscriber and hit the bell to be the first to know
Read The Sun: www.thesun.co.uk
Like The Sun on Facebook: www.facebook.com/thesun/
Follow The Sun on Twitter: twitter.com/TheSun
Subscribe to The Sun on Snapchat: www.snapchat.com/discover/The_Sun/1633225139