Iran's emergence from economic sanctions will help Europe to diversify its energy supplies, but the Islamic Republic will need to invest at least $150 billion in infrastructure to become a major producer, the head of Italy's Eni SpA said on Sunday.

"I'm very happy that Iran has returned because for us it means ... the European system will have a more diversified energy supply," Claudio Descalzi told RAI television.

"To make the big jump, which could take four or five years, a jump that could have a real impact on the global market ... Iran would need to attract $150 billion for development," he said.

"In today's market, finding $150 to $200 billion to invest in Iran is not something that can be done in a second."

Iran ended years of economic isolation on Saturday when world powers lifted sanctions in return for Tehran complying with a deal to curb its nuclear ambitions.

Eni was one of the main buyers of Iranian oil prior to the sanctions. Descalzi did not say how much oil Eni might be interested in purchasing now that the sanctions have been lifted. – Reuters