[People carry the body of a dead migrant from the vessel Topaz Responder as they arrive in the Sicilian harbour of Augusta]By Gabriela Baczynska BRUSSELS (Reuters) - The U.N. refugee agency warned on Tuesday that 2016 looked set to become the deadliest year on record for refugees and migrants crossing the Mediterranean to reach Italy and Greece, even though arrivals are down 40 percent from a year ago. The UNHCR said more than 300,000 migrants and refugees had arrived by sea to the shores of Italy and Greece so far this year, down from 520,000 in the same period last year. "At this rate, 2016 will be the deadliest year on record in the Mediterranean Sea," the agency said in a statement.