A man adjusts a Greek flag ahead of the visit of Greek Prime Minister Alexis Tsipras at the European Commission headquarters in Brussels February 4, 2015.

The European Central Bank has revoked a waiver that allowed banks to use Greek government debt as collateral for loans.

The ECB, in a statement late Wednesday, said it was no longer able to assume there would be a successful conclusion to the Greek government's bailout talks with its lenders.