ATHENS (Reuters) - Greek President Prokopis Pavlopoulos on Thursday ruled out a revision of an international treaty defining the borders of Greece and Turkey.  The Treaty of Lausanne defines the territory and the sovereignty of Greece and of the European Union and this treaty is for us non-negotiable.   It has no flaws, it does not need to be reviewed, or to be updated,  Pavlopoulos said during a meeting with Turkish President Tayyip Erdogan, on a two day official visit to the neighbouring country. Erdogan was quoted earlier in a Greek newspaper interview suggesting a revision to the 1923 Treaty of Lausanne, which established the borders of modern-day Turkey. In comments to Pavlopoulos, Erdogan said there were some details in the Lausanne Treaty which are not clear. 