As the international donors conference takes place in London, Israel is under international pressure to lift the siege on the Palestinians. Richard Falk is the new UN Special Rapporteur mandated to monitor human rights in the Occupied Palestinian Territories, but Israel has denied him a visa because of his past comments likening the Israelis' collective punishment to that of the Nazis. On the day he takes up his new post, Richard Falk talks to Stephen Sackur.