"Belarus must stop putting people's lives at risk," von der Leyen said in a statement on Monday, adding that "the instrumentalisation of migrants for political purposes by Belarus is unacceptable."
"The Belarusian authorities must understand that pressuring the European Union in this way through a cynical instrumentalisation of migrants will not help them succeed in their purposes," von der Leyen said.
She added that she had spoken to Polish Prime Minister Mateusz Morawiecki, Lithuanian Prime Minister Ingrida Šimonytė and Latvian Prime Minister Arturs Krišjānis Kariņš "to express the EU's solidarity and discuss with them the measures the EU can take to support them in their efforts to deal with this crisis."
"I am calling on Member States to finally approve the extended sanctions regime on the Belarusian authorities responsible for this hybrid attack," von der Leyen said.
Her statement also said that European Commission Vice-President Margaritis Schinas, "in coordination with High Representative/Vice-President Borrell, will travel in the coming days to the main countries of origin and of transit to ensure that they act to prevent their own nationals from falling into the trap set by the Belarusian authorities."
The European Union "will in particular explore how to sanction, including through blacklisting, third country airlines that are active in human trafficking," the statement continued.
"Finally, the Commission will explore with the UN and its specialised agencies how to prevent a humanitarian crisis from unfolding and to ensure that migrants can be safely returned to their country of origin, with the support of their national authorities."
Polish border guards, police and soldiers on Monday thwarted several attempts by migrants to force their way into the country via Belarus, government officials said, as the border crisis escalated.
The European Union has accused Belarus of encouraging thousands of migrants from the Middle East and Africa to cross into EU countries via Belarus, as a form of hybrid warfare in revenge for Western sanctions on Minsk over human rights abuses, the Reuters news agency reported.
Poland and the Baltic states have accused Belarus's strongman leader Alexander Lukashenko of organising a wave of illegal migrants seeking to enter the bloc as part of what officials have called a "hybrid war."
Source: IAR, PAP, Reuters, ec.europa.eu