Canadian Foreign Minister Lawrence Cannon is the latest voice to condemn Iran's nuclear program.
Cannon told the United Nations in a speech Saturday night that Canada is deeply concerned about Iran, as it was discovered Friday that the country has been developing a secret nuclear facility.
He condemned Iran for its "continued refusal" to listen to resolutions by the UN Security Council and the International Atomic Energy Agency.
Meanwhile, U.S. President Barack Obama has offered Iran "serious, meaningful dialogue," while warning that it will face greater isolation from the international community if the country fails to co-operate on nuclear nonproliferation.
"Iran's leaders must now choose," Obama said Saturday in his weekly online and radio address. "They can live up to their responsibilities and achieve integration with the community of nations, or they will face increased pressure and isolation and deny opportunity to their own people."
Obama demanded once again that Iran co-operate with the International Atomic Energy Agency, presumably to have its nuclear facilities inspected. Failing to do so will lead to greater pressure on Iran from an increasingly united international community, he said.
Iran agreed Saturday that it would allow UN nuclear inspectors to examine its new nuclear facility. The new facility will be operational "soon," a high-ranking official told Iranian television.
The U.S., Britain and France released evidence Friday at the G-20 meeting in Pittsburg that suggested Iran has been building a second secret uranium enrichment facility. Such action constitutes "a serious challenge to the global non-proliferation regime and continues a disturbing pattern of Iranian evasion," Obama said.
After that information about the new uranium enrichment plant was made public, Russia's President Dmitry Medvedev and China's Vice Foreign Minister He Yafei urged Iran to co-operate with the IAEA. But the Chinese official did not endorse penalizing Iran if it failed to co-operate.
Still, Obama said Iran faces growing international opposition to its nuclear program.
"On this, the international community is more united than ever before," he said. "All of the permanent members of the United Nations Security Council and Germany have made it clear that Iran must fulfill its responsibilities."
"My offer of a serious, meaningful dialogue to resolve this issue remains open. But Iran must now co-operate fully with the International Atomic Energy Agency and take action to demonstrate its peaceful intentions."
Obama's remarks came days ahead of key international negotiations, which he described as taking on "added urgency." The negotiations are scheduled to take place in Geneva on Thursday.
At a news conference in New York, Iranian President Mahmoud Ahmadinejad defended the construction of the second secret nuclear site.
"What we did was completely legal, according to the law. We have informed the agency, the agency will come and take a look and produce a report and it's nothing new," he said.
Ali Akbar Salehi, the head of Iran's nuclear program, said Saturday that UN inspectors will be permitted to visit the underground facility, which is still under construction. He didn't specify when the inspection could be carried out.
Salehi told Iran's state news agency that the facility is "a semi-industrial plant for enriching nuclear fuel." It's believed to lie in a mountainous north-western region of the country near the holy city of Qom.
Ahmadinejad said the plant won't be operational for another 18 months.