VIENNA, Dec 16 (Reuters) - The remaining parties to the 2015 Iran nuclear deal plan to meet on Friday at 1300 GMT to adjourn talks on salvaging the deal, three diplomats said on Thursday. The indirect U.S.-Iran talks on bringing both back into full compliance with the deal are in their seventh round. One of the diplomats said they were due to resume on Dec. 27, while another gave a time frame between Christmas and the New Year. Under the agreement, Iran had limited its nuclear program in return for relief from U.S., European Union and United Nations economic sanctions. Then-President Donald Trump, a Republican, pulled the United States out of the accord in 2018 and reimposed U.S. sanctions, prompting Iran to begin violating its nuclear restrictions in 2019. Trump"s successor, Democrat Joe Biden, has sought to revive the deal via indirect talks in which officials from other parties - Britain, China, France, Germany, Russia, as well as the European Union - shuttle between U.S. and Iranian diplomats because Tehran refuses to meet directly. Britain, France and Germany have sounded pessimistic about resuscitating the agreement, saying on Tuesday "we are rapidly reaching the end of the road" to save it as Tehran accused Western powers of engaging in a "blame game." read more