(Reuters) - A U.S. delegation will visit Iran to review energy investment opportunities while Tehran negotiates a final deal with world powers on its nuclear program, a senior oil ministry official told Mehr news agency on Monday.

The United States has imposed sanctions on Tehran which prohibit Americans from trading directly or indirectly with Iran's oil sector, government or individuals connected to the sector, including any financing.

U.S. companies are also prevented from investing in Iran's oil and gas industries or trading with them.

"It is forecast that by the visit of (the) American delegation this week and in the case of lifting sanctions on Iran's oil industry, we will witness involvement of major international American oil and gas companies in Iran in the future," said deputy Oil Minister Abbas Sheri-Moghaddam.

Friday is the last day of the week in Iran.

A tentative deal between Iran and the powers was reached in Switzerland on April 2 that cleared the way for a final settlement on June 30, in which Tehran would agree to restrict sensitive nuclear work in exchange for sanctions relief.

Sheri-Moghaddam did not reveal any details, but added that some "European-American companies" have expressed readiness to invest in Iran's new petrochemical projects.

Western sanctions have cut Iran's oil exports by more than half to around 1.1 million bpd from a pre-2012 level of 2.5 million bpd, with the loss of oil income making it difficult to invest in new development and pay for the equipment and services needed to keep its production operating smoothly.

The sanctions imposed by the United States and European Union on Iran since 2012 have led to the gradual departure of major Western oil companies from Iran.

Iranian officials have repeatedly said Teheran places no limitations on Western companies, including U.S. companies, investing in its oil and gas sector.

In 2013, Iran's Oil Minister Bijan Zanganeh said seven Western companies were welcome to return to Iran to explore oil after international sanctions are lifted, including the U.S. majors ExxonMobil and ConocoPhillips.

By Reuters