[Italian Prime Minister Renzi talks with German Chancellor Merkel as they arrive for a news conference at Chigi Palace in Rome]By Crispian Balmer ROME (Reuters) - Italy and Germany agree on how Europe should tackle the migrant crisis and oppose any move to fence off borders, but they are at odds over how to fund proposed initiatives, the leaders of the two countries said on Thursday. German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi warned that unless the European Union found a common migration stance, old nationalist ghosts would reawaken. "This is not a challenge for Greece, Germany or Italy, but these are challenges that have to do with the future of Europe." Immigration issues dominated talks between the two leaders, with both agreeing that more needed to be done to help African states stem migrant flows across the Mediterranean Sea.