(Reuters) -The U.N. aid chief on Friday said he was "deeply alarmed" by Israeli ministers' statements about "plans to encourage the mass transfer" of Palestinian civilians from the Gaza Strip to third countries and he called anew for a ceasefire. "Unless we act, it will become an indelible mark on our humanity," Martin Griffiths, the U.N. undersecretary for humanitarian affairs, told the U.N. Security Council. Griffiths painted a dire picture of a worsening humanitarian catastrophe in the Gaza S