OPEC will not take sole responsibility for propping up the oil price, Saudi Arabia’s oil minister said on Sunday, signaling the world’s top petroleum exporter is determined to ride out a market slump that has roughly halved prices since last June. Last November, Organization of the Petroleum Exporting Countries kingpin Saudi Arabia persuaded members to keep production unchanged to defend market share. The move accelerated an already sharp oil price drop from peaks last year of more than $100 per barrel that was precipitated by an oversupply of crude and weakening demand.