Amir Hossein Zamani-Nia told Shana that the first MoU dealt with strategic cooperation in the energy sector which was signed by Iran's Oil Minister Bijan Namdar Zanganeh and Russian Energy Minister Alexander Novak.
The official said that National Iranian Oil Company (NIOC) signed two agreements with Russia's Gazprom as well as two MoUs with Rosneft.
Russian oil producer Rosneft and the NIOC agreed an outline deal to work together on a number of strategic projects in Iran worth up to $30 billion, said Rosneft's Managing Director Igor Sechin.
Potential collaboration with Iran would further strengthen Rosneft's position in the Middle East, the company having already secured a number of deals in the region, including the acquisition of a majority stake in Iraqi Kurdistan's main oil pipeline, Reuters reported.
The recent deals appeared to be part of a strategy by President Vladimir Putin to boost Moscow's political and economic influence in the region.
The outline agreement on working with Iran was signed during Putin's visit on Wednesday.
Sechin said the preliminary deal paved the way for legally-binding documents to be signed within a year. Output from the joint project is seen plateauing at 55 million tons per year (1.1 million barrels per day), he said.
"We are talking about several oil and gas fields, which we will develop with our partners," Sechin told reporters, adding that Rosneft has invited Iran to develop offshore and other projects in Russia.
It is not yet clear how the investments will be split between the two companies.
Russia and Iran have long been working on oil-for-goods deals worth up to $20 billion.
Sechin said the preliminary agreement envisaged some swap deals, as well as oil and oil products deliveries.
Zamani-Nia said the sixth MoU was signed Between Iranian Oil Ministry and Gazprom.
Meanwhile, RIA news agency cited Russian Energy Minister Alexander Novak as saying on Wednesday that Russia and Iran will prepare by the yearend a legal framework for a project to deliver natural gas from Iran to India and will get down to practical work in 2018.
Novak also said that Gazprom plans to produce natural gas in Iran and will build a 1,200 km gas pipeline from Iran to India.