The US sanctioned a Chinese oil refinery as well as dozens of shipping firms and vessels that transport Iranian oil, as the Trump administration ramps up economic pressure on Tehran ahead of diplomatic talks.

The Treasury Department’s Office of Foreign Assets Control, or OFAC, said Friday it imposed penalties on Hengli Petrochemical (Dalian) Refinery Co., one of China’s smaller so-called teapot oil refineries that the department called “one of Tehran’s most valued customers.”