RIYADH, Nov 17, 2007 (AFP) - Venezuelan President Hugo Chavez opened an OPEC summit on Saturday with a chilling warning about 200-dollar oil if the United States attacks Iran in a speech that also urged the cartel to be more political.

But internal divisions about the role of the oil exporters' group were highlighted when King Abdullah of Saudi Arabia, OPEC kingpin and key US regional ally, sounded a moderate note, saying oil 'must not become an instrument for conflict.'