BEIJING, Jan. 5 (Xinhua) -- It is imperative for all parties to push the United States to unconditionally return to the Joint Comprehensive Plan of Action (JCPOA) as soon as possible and lift all relevant sanctions, a Foreign Ministry spokesperson said Tuesday.

Spokesperson Hua Chunying made the remarks at a daily press briefing when responding to the report that Iran has started injecting uranium gas in its Fordow Fuel Enrichment Plant as part of the process to enrich the mineral to a purity of up to 20 percent, while a U.S. State Department spokesperson said that Iran's move is an attempt to step up nuclear blackmail and will not succeed.

Noting that the Iranian nuclear issue is at a critical juncture with a complex and sensitive situation, Hua said China urges all parties to maintain calm and restraint, adhere to the consensus on upholding the JCPOA, refrain from actions that aggravate tensions, and leave room for diplomatic efforts and for the situation to turn around.

"The most urgent issue is that all parties should push the U.S. side to unconditionally return to the JCPOA as soon as possible and lift all relevant sanctions so as to create conditions for bringing the JCPOA back on track," Hua said.