The Iranian government said Wednesday it would revise how it governs oil and natural gas contracts, though sanctions must be lifted for full utilization.

Mehdi Hosseini, the director of a committee tasked with contract revisions, said Iran will be switching from a buy-back system to one based on joint ventures in the oil and natural gas sector.

Iran under the terms of the previous buy-back contracts paid contractors a set price for oil and natural gas produced. Under the planned new system, state-run energy companies will establish joint ventures with their international counterparts, who will be paid with a share of the output.

Hosseini said the new contract system was designed to bring more foreign investments into the Iranian energy sector.

"In order for international companies to be able to invest in Iran projects, the sanctions must be lifted so that they would be able to easily invest in Iran's oil projects," he said in a statement.

Iran secured modest relief from Western economic sanctions under the terms of an interim nuclear deal reached in November in Geneva, Switzerland. Though the Iranian government said it's ready to court more foreign investors, Washington said the country's energy sector is not yet open for business.

Hosseini said the terms of the new contract would be finalized before the end of the year.