The National Iranian Oil Company (NIOC) and Russian state-controlled energy giant Gazprom have signed a memorandum of understanding worth around $40 billion, according to the Iranian Oil Ministry's news service, SHANA.
The deal, agreed on July 19, coincides with Russian President Vladimir Putin's visit to Tehran for a summit with his Iranian and Turkish counterparts.
SHANA reported that Gazprom will offer its support to NIOC in the development of the Kish and North Pars offshore gas fields and also six oil fields.
It said that Gazprom will also be involved in the completion of liquefied natural gas (LNG) projects and construction of gas-export pipelines.
Iran has the world's second-largest gas reserves after Russia, but U.S. sanctions have prevented access to extraction technology and slowed development of gas exports.