The price rise Tuesday also came on the back of supply concerns out of South Sudan, which has shown no signs of restarting production after shutting down due to a protest of a transit-fee dispute with neighboring Sudan. Earlier, Sudan had seized South Sudan's export cargoes. Though it has released them, South Sudan didn't seem ready yet to restart output, cutting about 350,000 barrels a day of oil exports from the global markets. Meanwhile, the Organization of the Petroleum Exporting Countrie's (OPEC) Secretary General Abdalla Salem El-Badri told CNBC that even though there is at the moment no shortage of global oil supply, the European Union's decision to ban all Iranian crude exports in response to its nuclear development plans would most certainly lead to a spike in prices. "To take out 400-500,000 barrels a day in a matter of days, this will affect the price," he said. "Of course the price will go up." On Tuesday, an undercurrent of worries about Portugal's still elevated ten-year government bond yield and Greece's impasse on debt swap talks with private creditors had continued to threaten the upside momentum. Energy stocks were trading mixed. BP ( BP) was rising 1.4% to $44.75; Exxon ( XOM) was falling 1% to $84.60; Apache ( APA) was higher by 0.6% to $99.40; ConocoPhillips ( COP) was up 0.5% to $69.05; Halliburton ( HAL) was up 0.9% to $37; Weatherford International ( WFT) was up 0.6% to $17.02; and Baker Hughes ( BHI) was adding 1.2% to $50. -- Written by Andrea Tse in New York. >To contact the writer of this article, click here: Andrea Tse. >To follow the writer on Twitter, go to http://twitter.com/atwtse . >To submit a news tip, send an email to: email@example.com.