SINGAPORE: China Petrochemical Corp. (Sinopec Group) and China National Petroleum Corp. (CNPC), the country’s top state-owned refiners, are skipping Iranian oil purchases for loading in May after Washington ended sanction waivers to turn up pressure on Tehran, three people with knowledge of the matter said.The US has not renewed any exemptions from sanctions on Iran, taking a tougher line than expected on the expiry of the waivers. The waivers were granted last November to buyers of Iranian oil.China is Iran’s largest oil customer with imports of 475,000 barrels per day (bpd) in the first quarter of this year, according to Chinese customs data.Two of the sources said Sinopec and CNPC have skipped bookings for cargoes loading in May as the companies were worried that taking oil from Iran could invoke US sanctions and cut them out of the global financial system.A third source said Sinopec, which buys the majority of China’s Iranian oil imports, does not wish to breach a long-term supply contract, but has opted to suspend booking new cargoes for now due to the sanction worries.All those with knowledge of the matter requested anonymity due to the sensitive nature of the topic.Of the five supertankers that loaded Iranian crude in April for China, two have discharged, while another two are waiting off Ningbo and Zhoushan in eastern China to discharge, according to Refinitiv data and Refinitiv analyst Emma Li. A fifth tanker is heading to Shuidong in southern Guangdong province.The sources said they did not know how long the suspensions will last.Both Sinopec and CNPC declined to comment. The National Iranian Oil Company (NIOC) did not immediately respond to an email from Reuters seeking comment.The two firms took a similar move last October by skipping shipments for November, before Washington reimposed sanctions on Iran’s oil exports to push the Islamic Republic to renegotiate a deal to stop its nuclear and ballistic missile programs and curb its regional influence.They later resumed bookings after the US granted waivers to China and other seven global clients of Iranian oil, and purchased additional cargoes to make up the delayed shipments, according to the third source and trade flow data.“There are no nominations so far, but companies are trying to find some solution, such as offering to top up volumes in later months,” said the source.Sinopec agreed in 2012 to lift an average of about 265,000 bpd oil from Iran in a long-term deal that expires end of 2019.While Beijing has criticized the unilateral US sanctions on Iran and the end to the exemptions, companies are erring on the side of caution unless they receive a specific government mandate to keep ordering oil from Tehran, the first two sources said.CNPC, whose Iranian oil comes mostly from its investments at two Iranian oil fields, is also skipping imports for this month, said one of those sources.“For now it’s just not worth the risks as the volume is very small in (the company’s) overall purchases,” said the source.