BRUSSELS, June 21 (Reuters) - Representatives of Greece's creditors are set to meet at 1500 GMT on Sunday to discuss a possible deal, but the meeting can only be productive if Athens submits a new proposal they can discuss, EU diplomats said on Sunday.

"At this stage, the proposal is not yet available," one EU diplomat said. Separately, French President Francois Hollande said in Milan that Greece had now submitted new proposals.

Other sources in Frankfurt and in Brussels said that the European Central Bank's board would discuss the liquidity of Greece's banking sector at 0830 GMT on Monday.

The sources said that already Greek pre-orders for deposit withdrawals for Monday have reached 1 billion euros.

(Reporting by Jan Strupczewski; Editing by Alastair Macdonald)