SHANGHAI, Jan 15 (Reuters) - China reaffirmed its opposition to unilateral sanctions by the United States against Iran at a meeting between Foreign Minister Wang Yi and his Iranian counterpart, while backing efforts to revive a 2015 nuclear deal between major powers and Iran. A summary of Friday"s meeting between Wang and Iranian Foreign Minister Hossein Amirabdollahian in the city of Wuxi, in Jiangsu province, was posted on China"s foreign ministry website on Saturday. During his visit, Amirabdollahian is set to announce the launch of a 25-year cooperation agreement between the Islamic Republic and Communist-ruled China. Wang, who is also State Councillor, said the U.S. bore primary responsibility for the ongoing difficulties with Iran, having unilaterally withdrawn from a 2015 nuclear deal between the major powers and Iran. Under the terms of that deal, in return for the lifting of international sanctions, Iran would limit uranium enrichment activity, making it harder to develop nuclear arms - although Tehran denies having plans for nuclear weapons. Wang said China would firmly support a resumption on negotiations on a nuclear pact. But he said China firmly opposes illegal unilateral sanctions against Iran, political manipulation through topics including human rights, and interference in the internal affairs of Iran and other regional countries. The United States reimposed sanctions that badly damaged Iran"s economy after withdrawing from the nuclear pact in 2018, saying the terms did not do enough to curb Iran"s nuclear activities, ballistic missile program and regional influence. A year later, Iran began to gradually breach the accord, rebuilding stockpiles of enriched uranium, refining it to higher fissile purity and installing advanced centrifuges to speed up output. Iran and the U.S. remain locked in talks over whether a compromise can be found to renew the deal and dispel fears of a wider Middle East War. A source close to negotiations said on Friday that many issues remain unresolved. read more Wang, who earlier in the week met with several counterparts from Gulf Arab countries concerned about the potential threat from Iran, also said China hopes to set up a dialogue mechanism with Gulf countries to discuss regional security issues.