With nuclear negotiations dragging on, an Iranian energy official said a new type of oil contract is ready nonetheless for a possible post-sanctions era.

Iranian Oil Minister Bijan Zangeneh is on the cusp of formalizing a new contract model, said Mehdi Hosseini, the director of a ministerial contracts revision team. Sanctions pressure could ease if negotiators reach a formal nuclear deal by Tuesday and Iran expects a flood of foreign investments, the director said.

Iran aims to form joint ventures between the National Iranian Oil Co. and foreign energy companies, replacing a buy-back model where the host government pays a set sum for production volumes.

"This [type] of contract will be submitted to the government for final approval," Hosseini said.

Iranian crude oil exports are limited to around 1 million barrels per day and to six nations under the terms of existing sanctions. That's about half of the export potential for Iran, a member of the Organization of Petroleum Exporting Countries.

Sanctions on Iranian oil exports and other parts of the economy resulted in an economic contraction of 5.8 percent in 2012-13.

Iran's economy emerged from recession in late 2014, though sanctions still curb the country's ability to generate revenue from oil and gas sales. The Central Bank of Iran, however, said a nine-month growth rate of 3.6 percent represents an increase in $54 billion.

Parties to nuclear negotiations in Vienna said during the weekend they were committed to reaching a deal, though there are difficult issues ahead. Iranian Foreign Minister Javad Zarif said Monday his diplomatic partners "must choose between agreement and coercion."

Iranian officials last week said they'd continue with an "economy of resistance" by focusing more on parts of the economy isolated from sanctions.