Delegates from the U.S. oil industry are expected in Tehran to explore the possibility of conducting business there, Iran's deputy oil minister said Monday.

Iran is restricted to around 1 million barrels per day in exports to a few consuming nations. That's about half the level from before a joint arrangement with international negotiating partners went into force in late 2013. Exports are restricted to just six nations.

Deputy Oil Minister Abbas Moqadam said Monday that representatives from the United States are expected in Iran this week to hold talks with officials in his ministry as well as with domestic contractors working in the oil sector.

"It is predicted that, following the visit by the American delegation to Tehran and possible removal of sanctions against the oil industry, we will witness the presence of major international U.S. oil and gas companies in Iran in future," he said.

In mid-January, Mohsen Rezaei, secretary of the influential Expediency Council, said exports have dropped by 1.5 million barrels per day and inflicted more than $100 billion in revenue losses since 2013. Petroleum officials in Tehran have said, however, they expect foreign investors to "flock to Iran" in the wake of any sanctions relief.

The Iranian government is pressing for more sanctions relief from a framework agreement slated to take force in mid-2015.

Marie Harf, a spokeswoman for the State Department, said last month it was premature to consider what would happen if the framework agreement is finalized.

"The restrictions on oil purchases remain in place," she said. "So what will happen under a comprehensive joint plan of action, I just don't know yet."