The Organisation of the Petroleum Exporting Countries has quietly begun to reduce its oil production despite calls from the US and Europe for the group to pump more so that prices fall. Output from the core countries of the 13-member cartel last month fell to 27.3m barrels a day, down from the 27.6m b/d they produced in February and 27.8m b/d in January, the International Energy Agency, the western countries' watchdog, said yesterday in its monthly report. Production from Saudi Arabia, Opec's largest member, dropped marginally from January and was the same as February at 9.2m b/d.