The work group was held upon signing the draft of the Caspian Sea Legal Regime Convention by presidents of the five countries in Aktau, Kazakhstan.
The current two-day meeting is aimed at determining the methods of dividing the beginning point in the Caspian Sea.
Iranian delegation headed by director general of Iran Foreign Ministry for bilateral political relations and regional initiatives Reza Nazar Ahari attended the event.
Earlier on August 16, 2018, Foreign Minister Mohammad Javad Zarif said Iran believed that it should own 20 per cent of the Caspian Sea resources and the issue of an 11-per cent share originates from an illusory line related to the former regime of Iran.
The idea that Iran should possess 50 per cent of the Caspian Sea is wrong because in that case Turkmenistan and Azerbaijan would have no share, he added.
Zarif noted that the Convention on the Legal Status of the Caspian Sea does not allow the littoral states to use the waters for military purposes against other countries, expressing surprise that some friends were bringing such matters of national pride under question.