The world's major powers made progress in agreeing on possible new sanctions against Iran for refusing to suspend uranium enrichment but some differences remain, UN diplomats said. Foreign ministry political directors from the United States, Russia, China, Britain, France and Germany held a two-hour conference call Thursday to discuss what to include in a new UN Security Council resolution, the diplomats said. "They had a good productive discussion during which they made progress in agreeing on the elements of a resolution," the US State Department said in a statement. "A few more issues remain for discussion, and the political directors agreed to convene another conference call on Saturday morning." The State Department said it expects that ambassadors from the six countries "could begin drafting the text of a resolution next week." Iran's refusal to freeze all its enrichment-related activities prompted the UN Security Council on Dec. 23 to impose sanctions targeting its nuclear and missile programs and the persons involved in them. The council gave Teheran 60 days to halt enrichment or face additional measures. The International Atomic Energy Agency's report last week that Iran was expanding enrichment instead of suspending it set the stage for new UN sanctions to try to pressure Teheran to agree to a freeze ahead of negotiations on its nuclear program. Iran insists its nuclear program is aimed solely at producing nuclear energy - not nuclear weapons - and it has adamantly refused to halt it. UN diplomats said the six countries, which have been the key players in trying to negotiate with Iran, all believe the initial sanctions have had a positive effect on Teheran. Britain's UN Ambassador Emyr Jones Parry said recently that the new resolution would be looking at an "incremental" strengthening of sanctions. The US, Britain and France might want tough new sanctions, but will probably have to settle for less to ensure that Russia and China, which have close ties to Iran, won't use their veto power to block a resolution. That would ensure that the new resolution can be adopted unanimously - which all six countries appear to want so they can remain united in their stance on Iran. Some diplomats said the new measure may include travel bans, expand the list of technology and materials countries are banned from making available to Iran, and create stiffer economic sanctions including a ban on export guarantees to Iran, among other options. The diplomats spoke on condition of anonymity because the negotiations are private.