ISTANBUL—Turkish authorities on Thursday found seven more dead bodies near Turkey’s border with Greece, raising to 19 the number of migrants who have frozen to death at the frontier. Turkey has blamed Greece for the deaths, accusing Greek border guards of illegally pushing the migrants back over the frontier. Greece has strongly rejected the accusation. Turkish President Recep Tayyip Erdogan vowed on Thursday to expose what he said was Greece’s illegal pushback of migrants at every occasion. Turkey’s interior minister said Wednesday that 12 illegal immigrants had died after allegedly being pushed back into Turkey. One of the migrants was found alive but later died in a hospital. There was no information about the migrants’ nationalities. A statement from the governor’s office for the border province of Edirne said seven more bodies were found on Thursday. The state-run Anadolu Agency said gendarmerie forces were searching the area with the help …