Iran has warned its Gulf neighbours to not step in to make up for any shortfall in its oil exports under new Western sanctions, its OPEC representative said in comments published on Sunday. \"We would not consider these actions to be friendly,\" Mohammad Ali Khatibi was quoted as saying by the Sharq newspaper. \"If the oil producing nations on the Persian Gulf decide to substitute Iran\'s oil, then they will be held responsible for what happens,\" he said. Khatibi said Iran would consider any Gulf member of the Organisation of Petroleum Exporting Countries that \"cooperate with the adventurous (Western) nations in substituting Iranian oil to be accomplices.\" If they did so, \"one cannot predict the consequences,\" he was quoted as saying. Khatibi added that, if the Gulf nations do not cooperate with the West by pumping more oil, \"then its 90 percent probable that nothing would occur.\" The warning comes as the United States and the European Union step up sanctions to curb Iran\'s oil exports and revenue. Iran is the second-biggest oil exporter in OPEC, after Saudi Arabia, and it depends on petroleum revenues for more than half its state income. French Foreign Minister Alain Juppe said last Tuesday that unnamed oil producing countries will boost their output to make up for a planned EU ban on Iranian oil. \"Other countries are ready to increase production to avoid an effect on prices. We have made discreet contacts in this direction. The producers don\'t want to talk about it, but they are standing ready,\" he said.