That call will come amid increasingly acrimonious exchanges that illustrate the stark challenges that remain to a negotiated solution between Iran and the P5+1 group (comprised of the US, Russia, China, England, France and Germany) represented by Ms. Ashton.
The most recent letter late yesterday, from Mr. Jalili's deputy to Ashton's deputy, Helga Schmid, expressed "surprise" that Ms. Schmid's earlier letter "tabled issues that were a long way apart" from previous agreements and did not address Iran's counteroffer put forward in Baghdad in late May.
Jalili's deputy, Ali Bagheri, also asked why the P5+1 refused to meet at the experts level prior to the Moscow talks.
"If the agreements of each round of talks cannot be followed up at the level of deputies and experts, what guarantee will there be for the success of future talks?" Bagheri wrote in the letter that was leaked to Iranian media.