The EU is watching “with concern” the sudden migrant surge from Turkey to Greece and Bulgaria and stands ready to deploy its Frontex border guard agency to respond, Commission chief Ursula von der Leyen said Saturday.She tweeted that “our top priority at this stage is to ensure that Greece and Bulgaria have our full support”.Since Friday, thousands of migrants and asylum seekers have massed at Turkey’s border trying to enter EU member state Greece after Turkish President Recep Tayyip Erdogan…