Oil prices were mixed on Monday after weekend talks between Iran and world powers regarding the Islamic republic's nuclear program eased concerns over crude supplies, according to analysts. In New York trade the benchmark West Texas Intermediate for May delivery added 10 cents from Friday's close to end at $102.93 a barrel. In London, Brent North Sea crude for delivery in June slid $2.53 to stand at $118.68. Oil prices fell in early trade on reports that Iran and six major powers held "constructive" talks on Iran's nuclear program over the weekend, said IG Markets analyst Justin Harper. "This has helped take some of the 'war premium' out of energy prices." But US prices were more buoyant in the wake of robust US retail sales data for March, traders said. Saturday's nuclear talks between officials from Iran and diplomats from the so-called P5+1 group comprising the United States, Russia, China, Britain, France and Germany have largely been described as "positive" by both sides. "The weekend discussions between the P5+1 group and Iran suggest that Iran is being constructive enough to avoid any US/Israeli rush to judgment," said PVM brokers analyst David Hufton, referring to fears that Israel and the United States would launch an attack on Iran's nuclear facilities. In other oil news, Argentina announced it would forcibly seize a 51 percent shareholding in the country's biggest oil company, YPF, controlled by Spain's Repsol, despite warnings from Madrid and European Union officials. Also on Monday Russia's oil giant Rosneft detailed a strategic alliance with ExxonMobil including agreements to create joint ventures that will manage offshore exploration programs in the Arctic and Black Sea. "Today Rosneft and ExxonMobil enter offshore projects of unprecedented scale in the Russian Arctic and Black Sea regions, which are home to the world's largest hydrocarbon resources base," said Rosneft President Eduard Khudainatov. Rosneft subsidiaries will also gain 30 percent stakes in ExxonMobil's projects in West Texas, the US Gulf of Mexico and Canada, the statement said.