[An overcrowded dinghy with migrants from different African countries is followed by members of the German NGO Jugend Rettet as they approach the Iuventa vessel during a rescue operation in the Mediterranean Sea]By Gabriela Baczynska and Alastair Macdonald BRUSSELS (Reuters) - Encouraged by their success in halting a mass influx of refugees by closing Greek borders and cutting a controversial deal with Turkey, EU leaders are getting tough on African migrants too. A Brussels summit on Thursday will endorse pilot projects to pressure African governments via aid budgets to slow an exodus of people north across the Sahara and Mediterranean. It also wants swift results from an EU campaign to deport large numbers who reach Italy.