Senior officials from the United States and five other world powers will meet in Berlin this week to discuss ways to react to Iran's continued defiance of UN Security Council demands to stop uranium enrichment, diplomats said Tuesday. The diplomats, who spoke on condition of anonymity because they were not authorized to divulge the information, said US Deputy Secretary of State Nicholas Burns would be joined in the German capital on Thursday by counterparts from Russia, China, Britain, France - the other UN Security Council members - as well as Germany and a representative from the European Union. The planned meeting comes less than a week after a similar gathering Wednesday in London and amid signs that Tehran continues to ignore the council's ban on its enrichment program, despite two sets of UN sanctions imposed on the Islamic republic. It also follows on recent talks between Ali Larijani, Iran's top nuclear negotiator, and Javier Solana, the EU's senior foreign policy envoy. The talks are meant to seek a common basis for renewed talks between Iran and the six powers centered on a stop to all activities linked to enrichment, which can generate both nuclear power and the fissile material for warheads. Both envoys said after their talks last month that some progress was made, with diplomats familiar with their meeting saying the two had touched on the concept of a "double time out" - a simultaneous freeze of such enrichment activities in exchange for a commitment not to impose new UN sanctions. The "double time out" concept is the brainchild of International Atomic Energy Agency chief Mohamed ElBaradei and is part of a confidential document made available to the AP. The one-page document, based on a Swiss initiative, proposes that during such a double-moratorium "Iran will not develop any further its enrichment activities," and the six powers "will not table any additional U.N. resolutions and sanctions." Still, Iran publicly opposes any suspension to its enrichment activities. Instead, there are indications it is expanding its program Diplomats told the AP last week that Iran had recently set up more centrifuges at its underground uranium enrichment plant at Natanz, bringing the number of machines ready to spin uranium gas into enriched form to more than 1,600. An International Atomic Energy Agency document obtained last month said the Islamic regime was running more than 1,300 centrifuge machines to enrich uranium at Natanz. Its ultimate goal is to have 50,000 centrifuges. That would be enough to supply fuel for what Iran says is a planned network of atomic reactors to generate electricity. Or it could produce material for a full-scale nuclear weapons program.