WASHINGTON -- Iranian officials now say their country is open for business after the signing of an interim deal on its nuclear program last fall— and are taking concrete steps to facilitate trade with international partners.

Speaking to the press in Belgium on Sunday, Iranian Foreign Minister Mohammad Javad Zarif made a direct reference to a repeated line from White House officials that Iran is not, in fact, open for new or revisited trade contracts, so long as sanctions passed by the US, European Union and United Nations remain in place.

"Iran is open for business" nevertheless, Zarif said.

Iran's Petroleum Ministry is acting on that declaration, presenting new models for development projects that might entice foreign direct investment.

The models offer oil firms long-term contracts over crude sites of up to 25 years— a significant shift from previous short-term models of roughly 5 years, which were unpopular even before global sanctions hit Iran's economy hard in 2011.

Iran's oil minister Bijan Zanganeh acknowledges that big companies will likely refrain from returning until sanctions are fully lifted, Iran's state-run news media reported.

But the ministry feels "obliged to take action for safeguarding the oilfields and enhancing [production] capacities,” he said.

“We welcome the presence of all international oil companies, including American companies, to develop oil and gas fields and enhance [production] capacities,” Zanganeh added.

US officials this week said that, even if a comprehensive deal is reached on Iran's nuclear program through negotiations this year, Congress' embargo on Iranian oil will still remain in place until a deeper rapprochement takes place between the two nations.

Should businesses proceed with contracts in violation of sanctions, "we will come down on them like a ton of bricks," Obama said two weeks ago in a joint press conference with French President Francois Hollande from the White House.

"With respect to the sanctions that we control," Obama added.

Both Obama and US Secretary of State John Kerry have expressed concerns to EU leadership over reports that expansive European trade delegations have traveled to Tehran, exploring new business ventures.

"The Secretary and the President wouldn’t have raised this if they didn’t think that a stronger case still needed to be made," State Department spokeswoman Jen Psaki said during Hollande's visit.

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