Despite an atmosphere of good will, nuclear talks between Iran and six world powers have progressed "with much difficulty and slowly", Iranian news agency Fars reported on Friday.

The Islamic Republic and the P5+1 powers met for the latest round of negotiations starting on Wednesday in Vienna.

The "negotiations are conducted under an atmosphere of good will, but are moving with much difficulty and slowly", Fars quoted Iran's deputy chief negotiator Abbas Araqchi as saying after talks on Thursday.