ROME, Dec 8 (Reuters) - Pope Francis broke down and cried on Thursday as he mentioned the suffering of Ukrainians during a traditional prayer in central Rome.Francis broke down during a traditional prayer to the Madonna at the foot of a statue on the Feast of the Immaculate Conception, a national holiday in Italy."Immaculate Virgin, today I would have wanted to bring you the thanks of the Ukrainian people (for peace)," he said before being overwhelmed by emotion and having to stop.When he was able to, he continued: "Instead, once again I have to bring you the pleas of children, of the elderly, of fathers and mothers, of the young people of that martyred land, which is suffering so much."Since Russia invaded its neighbour in February, Francis has mentioned Ukraine in nearly all his public appearances and has grown increasingly critical of Moscow."