China’s Ministry of Commerce said on Saturday it had issued an injunction to block U.S. ​sanctions imposed on five Chinese refiners accused ‌of buying Iranian oil, according to state news agency Xinhua.

The ministry named the five as Hengli Petrochemical (Dalian) Refinery, and ​so called ‘teapot’ refineries Shandong Jincheng Petrochemical Group, Hebei ​Xinhai Chemical Group, Shouguang Luqing Petrochemical and Shandong ⁠Shengxing Chemical.

In April, the U.S. Treasury imposed sanctions ​on Hengli Petrochemical, accusing it of buying billions ​of dollars in Iranian oil, in an escalation of Washington’s long-running effort to curb Tehran’s oil revenue.