BRUSSELS (Reuters) - European Council President Donald Tusk canceled a trip to Israel and the Palestinian Territories planned for this week due to a  critical moment  in Brexit negotiations, an EU official said on Monday. Tusk, who scheduled a meeting in Brussels at short notice on Monday with British Prime Minister Theresa May, will chair an EU summit next week that London hopes will give the go-ahead to opening talks on post-Brexit trade relations. On Wednesday, Tusk had been due to meet Palestinian Prime Minister Rami Hamdallah in Ramallah and Israeli Prime Minister Benjamin Netanyahu in Jerusalem. 