Mr Tusk, a former President of the European Council and now leader of Poland’s main opposition party, Civic Platform, has called on EU member states to come together and use all available methods to bring peace to the region and prevent a further humanitarian crisis. Thousands of migrants, mostly from the Middle East, Afghanistan and Africa, have been trapped at the border between Belarus and Poland as tensions boil over between Minsk, Warsaw and the EU.
Officials in Poland and Brussels have accused Belarussian President Alexander Lukashenko of encouraging migrants to cross the border in retaliation to sanctions imposed over human rights abuses.
Polish troops have been deployed to the frontier and erected makeshift razor wire fences to prevent the flow of people.
Desperate migrants, many of whom from war-torn countries, have been left abandoned without food and water at the barricade – and some have even attempted to tunnel their way through.
In a letter published on Twitter, Mr Tusk called for immediate action from the bloc and warned things “may get out of control”.
The 64-year-old wrote: “I am addressing you, the leaders of EU Member States with an earnest appeal for full solidarity with Poland and Lithuania in the face of the growing crisis on the border with Belarus.
“Irrespective of your views regarding migration and your evaluation of the internal situation in Poland, we must, I underline, we must, as a political community, use all available means of pressure in order to contain the escalation of tension on the Eastern border of the (European) Union.
“For all, it should already be clear that this crisis has been cynically provoked by Alexander Lukashenko, whose goal is to destabilise Poland, Lithuania and the whole of the Union. At any time the situation may get out of control.”
He added: “The fundamental safety and security of our community are at stake. There is no more time or space for hesitation.
During a crisis meeting on Wednesday, EU diplomats said to decision by Belarus to encourage migrants crossings into Poland can be considered a “hybrid attack” and threatened further sanctions.
EU Council President Charles Michel said: “We are facing a brutal hybrid attack on our EU borders.
“Belarus is weapon migrants’ distress in a cynical and shocking way.”
European Commission President Ursula von der Leyen insisted sanctions could be imposed as early as next week on around 30 Belarussian individuals and its national airline.
She said: “Very rapidly at the beginning of next week there will be a widening of the sanctions against Belarus.
“We will look into the possibility of sanctioning those airlines who facilitate human trafficking towards Minsk and then the EU-Belarus border.”