The remaining Iran nuclear deal signatories reaffirmed their commitment to the Joint Comprehensive Plan of Action (JCPOA) and criticized the United States for its unilateral sanctions during a meeting on Sunday, according to a Chinese delegate. 

"I have two take-away messages from today's meeting," said Fu Cong, director general of the Department of Arms Control at the Chinese Foreign Ministry, at a press conference following the meeting. "First, all sides have expressed their commitment to safeguard the JCPOA and to continue to implement the JCPOA in an objective manner and a balanced manner." 

"The second point I take away from the meeting is that all sides have expressed their strong opposition against the U.S. unilateral imposition of sanctions, especially the extraterritorial application of the sanctions, and they also expressed support and appreciation of China's efforts to implement the JCPOA, in particular China's effort to maintain normal trade and oil relations with Iran," Fu said. 

Iran's senior nuclear negotiator Abbas Araqchi called the talks "constructive." 

"Discussions were good. I cannot say that we resolved everything. I can say there are lots of commitments," Araqchi added. 

The meeting was convened at the request of France, Germany, Britain and Iran to examine issues linked to the implementation of the JCPOA in all its aspects, according to diplomatic sources based in Vienna. 

At the meeting, China urged the three European countries to expand Instrument in Support of Trade Exchanges (INSTEX), a payment system to facilitate trade between the EU and Iran to get around U.S. sanctions, and open it up to third countries, said Fu. 

There were tense moments but on the whole the atmosphere was "professional," he said. 

There was a general agreement that a foreign ministers' meeting may be held, but more preparations are needed for this meeting to happen, Fu said. 

The JCPOA was inked in 2015 between Iran and the United States, France, Russia, Britain, Germany, Russia and China. Washington unilaterally withdrew from the landmark deal last year and resurrected sanctions on Tehran.