In the following link you can find the message of greetings published in the newsportal of KKE in greek:
Dear Comrades,
At this particular and crucial period of the struggle of
          the Sudanese peoples against imperialism and its local lakays
          ,and overthrowing of the ruling military-civilian
          authority,the Sudanese Communist Party conveys its
          revolutionary greetings to the 21st Congress of the Communist
          Party Of Greece,wishing the Congress every success in its
          deliberations to once more assert the leading role of CPG on
          the struggle of the labour and people movements for socialism
          in Grece.
The SCP,basing itself on the combative and fraternal
          relations that are cemented through years of cooperation and
          solidarity stress the recognition of the important role played
          by the CPG in reviving and developing the international
          communist and workers movements.
On many occasion our Party has attended several Congresses
          of the CPG.WE were witnesses to the creative debates that
          characterized your previous Congresses.WE are sure that the
          21st Congress will add not the experience and the future of
          the struggle of the Greek labour movement,but will form an
          important contribution to the struggle of the international
          working class movement.It will help to raise to higher levels
          the banners of proletariat internationalism..
Secretariat of the CC of the SCP
