WARSAW, April 15 (Reuters) - Poland and Hungary have decided to ban imports of grain and other food from neighbouring Ukraine to protect the local agricultural sector, the two governments said on Saturday, after a flood of supply depressed prices across the region. In a letter to the European Commission last month, the prime ministers of five eastern European countries said the scale of the increase in products like grains, oilseeds, eggs, poultry and sugar had been "unprecedented", and said tariffs on Ukrainian agricultural imports should potentially be considered. "Kaczynski said Poland was ready to start talks with Ukraine to settle the grain issue