UN Secretary-General Ban Ki- moon on Wednesday urged Iran not to take any steps to block the Strait of Hormuz, which sees 20 percent of the world's oil flows annually, saying that this is important for international trade and commerce.

Ban, who spoke at his first press conference on Wednesday since he began his second five-year term on Jan. 1, said, "This is a very important area for international trade and commerce, the Strait of Hormuz."

"The free passage of any ships in open seas should be respected and protected in accordance with relevant provisions of the Law of the Sea," he said.

Iranian military and political leaders have threatened to close the Strait of Hormuz if increased Western sanctions over Tehran's suspect nuclear activities halt Iran's exports.

Tehran denied the U.S. and European allegations that the Islamic republic is developing nuclear weapons, insisting on its previous claims that its nuclear program is for peaceful purposes.

Meanwhile, the secretary-general, who voiced his concerns over the Iranian nuclear program, called on all parties concerned to find "a peaceful resolution" of the issue in association with Iran 's nuclear program.

"I have been speaking with Iranian leaders many times directly and through my public statements that the onus is on the Iranian side to prove that their nuclear development program is genuinely for peaceful purposes," he said.

"And I am concerned by the most recent report of the International Atomic Energy Agency indicating that their program has something to be related with the military dimension," he said. "That they have to prove; that their nuclear program is for peaceful purposes. And they should fully cooperate with the IAEA. "

The secretary-general said that he has been urging these members of E3+3 and Iran to engage in a dialogue.

The E3+3 members include the five permanent members of the UN Security Council -- Britain, China, France, Russia and the United States -- and Germany, the six countries trying to resolve the decade-long standing over Iran's nuclear program at the negotiating table.

"There is no alternative to the peaceful resolution of this," he said. "At the same time, I have been urging the concerned parties to first of all to try to defuse the tension. These rhetorics are not helpful."

The Vienna-based IAEA, the UN nuclear watchdog, on Monday confirmed a planned Jan. 29-31 visit to Iran, saying that the overall objective was to "resolve all understanding substantive issues" linked to Iran's disputed nuclear program.