ROME - Diplomats from the United States, the European Union and other allies agreed on Tuesday to step up pressure on Iran to force it to resume talks over its nuclear program, an Italian diplomatic source said.The diplomats from the so-called "group of like-minded nations" met in Rome to discuss further sanctions against Iran, which could include a possible EU oil embargo.RELATED:'Iran could assemble nuclear bomb in under a year'Iran says invites UN nuclear agency to visit"The participants repeated the need for Iran to conform to resolutions of the United Nations and the IAEA (the UN International Atomic Energy Agency), and asked the country to satisfy demands by the international community for timely and immediate clarifications on its nuclear program," the source said."The participants expressed a strong determination to continue to work together to reinforce pressure on Iran to re-start negotiations," he added, giving no further detail.Iran faces tightening sanctions over a nuclear program it says is for peaceful power generation, but which its foes suspect is aimed at developing nuclear weapons.The closed-door meeting took place under the auspices of the Italian foreign ministry. Diplomats said earlier it would consider the arguments around a possible EU oil embargo against Iran. A decision may be made when EU foreign ministers next meet in January.Participants were countries that have imposed bilateral sanctions on Iran over its nuclear program that go beyond UN Security Council sanctions.The group includes the United States, the European Union and several European nations, Australia, Japan, South Korea and other countries but it was not clear if all of them were represented. The United States attended.The small informal group has been meeting for two years and its goal is to share information and discuss the next steps in the sanctions process.The United States has long banned Iranian crude oil imports and last week Congress voted through restrictions on dealing with the Iranian central bank.The White House must decide whether or not to grant waivers to major Iranian oil importers like China, India and South Korea that need to deal with the bank to pay for Iran's crude.In Vienna, an Iranian envoy said Tehran had invited the UN nuclear watchdog to visit for talks and would be ready to discuss concerns about its disputed atomic ambitions.Western diplomats tend to see such invitations as attempts by Iran, a major oil producer, to buy time and ease international pressure without heeding UN demands to curb nuclear work which could be used for making atomic bombs. Previous visits to Iran by senior IAEA officials have failed to make significant progress towards resolving the long-running row over Iran's nuclear program, a dispute which has the potential to spark a wider conflict in the Middle East.