Iranian Foreign Minister Hossein Amir-Abdollahian held a phone conversation with his Russian counterpart on Tuesday to discuss bilateral relations and Caucasus regional developments, Xinhua reported, citing a statement by the Iranian Foreign Ministry.

In the phone call, Amir-Abdollahian and Sergei Lavrov highlighted the determination of the two countries' presidents to further develop bilateral relations, said the statement published on the ministry's website.

The two top diplomats also discussed continuing regional negotiation mechanisms, including the "3+3" format that comprises three Caucasian states of Armenia, Azerbaijan and Georgia and their neighbors Russia, Turkey and Iran for ensuring lasting peace, stability and cooperation in the region.

The two ministers also talked about the holding of the second meeting of the foreign ministers of Iran, Russia, Turkey and Syria to rebuild ties between Damascus and Ankara.

The Iranian foreign minister expressed surprise at the contents of a part of a joint statement recently issued by the Gulf Cooperation Council (GCC) and Russia questioning Iran's sovereignty over the three Gulf islands of Abu Musa, the Greater Tunbs and the Lesser Tunbs, stressing that these islands belong to Iran "historically and forever."

Amir-Abdollahian underlined that Iran's independence, national sovereignty and territorial integrity are "absolutely non-negotiable."

He noted that ties between Iran and Russia have "strong foundations," calling for refrainment from any move that would harm the deep ties.