* French minister wants talks based on U.S. proposals
* Warns of tough days ahead if negotiations remain blocked
By Crispian Balmer
RAMALLAH, West Bank, June 2 (Reuters) - French Foreign Minister Alain Juppe made a last ditch effort on Thursday to revive peace negotiations between Israelis and Palestinians before a likely showdown at the United Nations in September.
U.S.-brokered talks collapsed last year in a dispute over Jewish settlement building, and the Palestinians say
