(Bloomberg) – Russia started swapping oil products with Iran, Interfax reported, the latest sign of deepening ties between the two sanctioned countries pushed closer by Russia’s war in Ukraine.

The range of swapped products will be expanded, Interfax cited Deputy Prime Minister Alexander Novak as saying, without giving further details, after a meeting with Iranian Oil Minister Javad Owji in Grozny.

The talks also covered potential Russian participation to increase Iranian oil production, the development of ports in the Mediterranean and Caspian Seas and an international north-south freight corridor connecting Russia to India via Iran, according to reports by Interfax and Tass.

Increasingly isolated by US sanctions, Moscow and Tehran have sought to deepen their economic and military partnership significantly since Russia’s invasion of Ukraine in late February. The Islamic Republic also faces more sanctions over its reported role in providing armaments to Russia for the conflict.

Iran is also seeking a gas swap deal with Moscow, under which it would import Russian gas via an intermediary country to boost exports from the Islamic Republic, as well as investment in a stalled LNG project and pipeline to Pakistan. Gas swap issues “are still being worked out,” Novak said, without elaborating.

Russian gas giant Gazprom PJSC may sign deals on projects in Iran by the end of November, Novak added.

Iran and Russia have signed $6.5 billion of oil and gas contracts as part of a memorandum of understanding that envisages up to $40 billion of deals, Iran’s semi-official Fars News cited Deputy Foreign Minister for Economic Affairs Mehdi Safari as saying on Monday.

Russian-Iranian ties are “of a strategic nature,” Novak said. “We aim to make every effort to develop these relations.”