The oil price of the Organization of the Petroleum Exporting Countries (OPEC) rose slightly at mid-week and hovered at 111.48 dollars, the group said Thursday. OPEC\'s basket price crept up 0.13 dollars per barrel (159 litres) on Wednesday. In contrast, benchmark brands in the United States and Europe fell steeply, as news of rising petrol inventories in the US created worries about slowing demand.