A sustained $10 per barrel increase in crude prices reduces growth in developing countries by 1.5%, oil minister S Jaipal Reddy said on Wednesday in Vienna, where crude producers of OPEC are meeting this week. ?There could not be a more direct cause and effect relation than high oil prices retarding economic growth of oil-importing countries,? Reddy said, a copy was issued to reporters by the petroleum ministry in New Delhi. ?We have seen evidence of this in our own country: India?s GDP grew at 6.9% in last fiscal year down from the 8% plus growth rate experienced in the past few years?.