The United States is calling on the Latin American states being toured by Iranian President Mahmoud Ahmadinejad to try their best to persuade the Islamic republic to change the course over its controversial nuclear program, the U.S. State Department said on Monday.

Department Spokeswoman Victoria Nuland said that Iran has " obviously carefully" chosen Venezuela, Nicaragua, Cuba and Ecuador for its president to make a tour.

"We are, meanwhile, calling on all of these countries to do what they can to impress upon the Iranian regime that the course that it's on in its nuclear dialogue with the international community is the wrong one," she told reporters at a regular press briefing.

"And, frankly, we think it's in the interest of all countries, including the countries that he (Ahmadinejad) is visiting in Latin America, that Iran proves the peaceful intent of its nuclear program to the world," she added.

The West alleges that Iran is pursuing nuclear bombs through its nuclear program, which Tehran insists is for peaceful purpose only.

The United States and its European allies are considering expanded sanctions against Iran to cover its oil exports, prompting the latter to threaten in late December to close the Strait of Hormuz, one of the world's most critical oil routes. The Pentagon then warned against such a move.