The basket price of the Organization of the Petroleum Exporting Countries (OPEC) retreated below the 70-dollar mark Monday, the Vienna-based Group announced Tuesday. One barrel (159 liters) of OPEC-produced crude fell to $69.24 at the start of the week, $1.21 dollars lower than last Friday. Last week the price moved about $70 dollars for the first time since October 2008. OPEC's 12 member countries produce some 34 per cent of the world's oil.