Fourteen European Union countries on Monday expelled Russian diplomats, a top official said, after the bloc last week sided with Britain in blaming Moscow over the poisoning of a former Russian spy.
"Already today, fourteen member states have decided to expel Russian diplomats," Tusk told a news conference in the Black Sea city of Varna.
"Additional measures, including further sanctions within the common EU framework, cannot be excluded in the coming days and weeks," he said.