The heads of the EU, IMF, European Central Bank and the eurozone on Friday will discuss a last-ditch reform plan that Greece submitted in a bid to avert financial collapse and exit from the eurozone, EU sources said.

"We must speak at the highest level," one source told AFP ahead of the conference call at 1100 GMT between Jean-Claude Juncker, Christine Lagarde, Mario Draghi and Jeroen Dijsselbloem.