Iran has announced plans to strengthen energy cooperation with Russia but stressed that an oil-for-goods deal had not been discussed.
"Iran and Russia have agreed to cooperate in the energy field," said Ali Majedi, Iran's deputy oil minister, as quoted by ISNA news agency.
"We will develop cooperation in oil, gas, petrochemicals and refineries," he said, adding that "the issue of an exchange of goods for oil is absolutely not on the agenda".
The United States has shown "serious concern" over suggestions that Moscow and Tehran were seeking to arrange a deal that could evade US sanctions imposed on Iran over its nuclear programme.
Washington first imposed sanctions on Tehran in 1979 after the dramatic hostage crisis at the US Embassy in Tehran. The penalties have been toughened over the years, while the US has also led the passage of sanctions measures through the United Nations Security Council.
The latest announcement was made as Russia's Energy Minister Alexander Novak attended the Iran-Russia business council event in Tehran.
He is due to meet with Iran's Energy Minister Hamid Chitchian as well as the Oil Minister Bijan Namdar Zanganeh.
"Russia will participate in the construction of eight power plants with a total capacity of 2,800 megawatts," Chitchian said after meeting with Novak.
The allies had previously announced a deal to boost Iran's energy infrastructure over a five-year period.