By Yannis Behrakis and Renee Maltezou ATHENS, Jan 19 (Reuters) - Hundreds of demonstrators on Saturday paraded the coffin in central Athens of a Pakistani immigrant who was stabbed to death earlier this week, praying and opening the casket to show his face in protest at racist attacks in the country. About 3,000 immigrants and human rights activists later gathered in the city's central Omonia square to demonstrate against racism, holding banners reading "Neo-Nazis out" and "Punishment for the fascist murderers of Shehzad Luqman".