WASHINGTON (Reuters) - There was no room for slippage in Greece's economic rescue package and failure to implement agreed policies could trigger an "unsustainable debt dynamic," a senior International Monetary Fund official said on Thursday. The biggest risk to implementation of Greece's new IMF-EU program is that Athens delays needed economic reforms to address large competitiveness gaps, Poul Thomsen, the IMF mission chief to Greece, told a conference call with reporters. ...