The European Union will impose sanctions against Russia for recognizing seperatist regions in eastern Ukraine, which is a blatant violation of international law as well as of the Minsk Agreements, officials said Monday.

EU Commission President Ursula von der Leyen and Council President Charles Michel said in a joint statement that the recognition is "a blatant violation of international law."

"The EU and its partners will react with unity, firmness and with determination in solidarity with Ukraine," they said.

Just before Putin signed the decrees recognizing the two pro-Russian rebel-held parts of Ukraine and signing them on to a "mutual assistance" pact with Russia, EU foreign policy chief Josep Borrell warned that sanctions would ensue.

Borrell said he would "put the sanctions on the table" for EU foreign ministers to decide whether to adopt them if Putin went ahead.

The EU has also warned it will impose unprecedented sanctions on Moscow if it invades Ukraine after it deployed an estimated 150,000 soldiers to the border.

Von der Leyen early Monday told Germany's ARD broadcaster that "if Vladimir Putin starts a war, we will respond with the most powerful lever we have: Economic and financial sanctions, because the economy is Russia's weak point".

She said: "Financial sanctions would mean that Russia would be virtually cut off from international financial markets."