KYIV/WARSAW/LONDON, Nov 17 (Reuters) - Ukraine has few viable options currently to boost grain exports by rail, road or river barge anytime soon if a United Nations-brokered deal with Moscow to export by sea runs into trouble. Ukraine has shipped grain by truck and train via its western border and through small Danube river ports in the south west. But the capacity on those routes is much smaller than from its sea ports - meaning there is no significant plan B if the sea corridor falters. "Rail and truck capacity can maybe be increased 3-5% but no more, because the infrastructure of Europe can't absorb our grain. They are not ready on truck, on rail, on river barge, on storage, to accept this grain at volume," he said.

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