The discussions to salvage the 2015 Iran nuclear deal will continue on Monday, according to two sources involved.

"Normally, it is not popular to conduct serious business between the Catholic Christmas and the New Year," said Mikhail Ulyanov, Russia's chief envoy to the discussions, on Thursday.

Talks with Iran on restoring 2015 nuclear deal suspended | Iran nuclear deal  | The Guardian

"In this particular case, this is an indication that all negotiators don't want to waste time and seek for the quickest restoration of the JCPOA," he added, referring to the deal's acronym, the Joint Comprehensive Plan of Action.

The meeting will be attended by representatives from China, France, Germany, Russia, the UK, and Iran, according to the European Union's foreign service.

"Participants will continue discussions on the prospect of the US possibly returning to the JCPOA and how to ensure full and effective implementation of the accord by all parties," the External Action Service said in a statement.