South Korea and Iran have increased cooperation with a maritime pact that also involves its classification societies.
Korean companies will gain greater access to the Middle East country's markets, while vessels from both nations will pass more easily through their territorial waters.
The Yonhap news agency said the two sides had tried unsuccessfully to implement a similar pact in 1998.
Class society Korean Register of Shipping and its Iranian counterpart have agreed a joint venture to encourage engineering projects.
The Mehr News Agency said a deal has also been signed that will see South Korea pump in $15bn to develop Iran's oil production capacity.
South Korean steelmaker Posco has said it will help build a $1.6bn mill in southeastern Iran.
