[Refugees and migrants are seen inside a terminal, moments after arriving aboard the Tera Jet passenger ship at the port of Piraeus, near Athens]European Union envoys agreed a new set of demands for Greece to fix its handling of irregular migrants on Wednesday, moving forward a process that could see frontier checks in Europe's passport-free Schengen zone extended for up to two years. EU diplomatic sources said a meeting of ambassadors from the 28 member states approved a second set of recommendations to Greece to end serious deficiencies in its control of its part of the Schengen area external border within three months. Should it fail to implement all the measures, which few expect Athens to be able to do, an unprecedented measure under the Schengen treaty would allow states inside the zone to impose checks on their own borders -- as some including Germany have already done in response to movements of migrants from Greece.