The United States and Iranian officials meet in Vienna for a final round of talk on Iran's nuclear program. However, a top U.S. official says negotiators may not reach an agreement by the time limit of June 30.U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif are planning private discussions in the Austrian capital. Others expected to take part in the talks are the "P5 plus one" nations. They are the five permanent members of the United Nations Security Council and Germany.The U.S. official said negotiators remain "committed" to the June 30 deadline but talks may continue beyond that date. The official added that all parties in the talks want to get a good agreement. But Obama administration spokesman, Josh Earnest, said there are no immediate plans to extend the deadline beyond Tuesday."The negotiations continue to be difficult but there continues to be a good faith effort on both sides to try to complete them in the timetable that we've laid out."Iran reached a framework agreement with the U.S., Russia, China, France, Britain and Germany on April 2. The agreement would permit inspections of nuclear sites and place limits on Iran's ability to enrich uranium, which can be used as fuel for a nuclear weapon. In exchange, Iran would receive relief from international sanctions. However, negotiators are still working on details of the plan.One debated issue in negotiations is when sanctions will be lifted. Iran wants an immediate end to sanctions if an agreement is reached. The restrictions have seriously hurt the county's economy. Other countries involved in the negotiations want sanctions to be removed in steps over time. They also want a process to verify that Iran is observing the agreement.The two sides also disagree over inspections of suspected nuclear centers. Iran's spiritual leader, Ayatollah Ali Khamenei, said Iran will not permit international inspectors to see military sites, scientists or documents. He spoke Tuesday on state television. He rejected limitations on the countries nuclear research and development lasting 10 to 12 years. And he demanded that sanctions be lifted upon signing the deal instead of in stages. In previous statements, the religious leader had expressed support for the talks.Secretary Kerry answered saying the Iranian leader's comments were not new. He said, "What matters ...is what is agreed upon within the four corners of the document, that is what is yet to be determined."Mr. Kerry added that if Iran fails to abide by the framework agreement reached in Lausanne, Switzerland, "there will not be an agreement."Former Ambassador James Jeffrey is one of several former officials to sign an open letter expressing concern the agreement may not be a good one. Five of those officials have served in the administration of President Obama. Mr. Jeffrey said those who signed the letter are concerned the administration will offer too many concessions. They urged tough inspections, long-term limits on nuclear research, full information on Iran's past activities and a gradual reduction in sanctions.Negotiation between Iran and the six powers have lasted for two years. There already have been two extensions of negotiating deadlines. Mark Fitzpatrick of the International Institute for Strategic Studies said, "The comprehensive deal, if and when it is struck, needs to be clear and detailed as to what is allowed and what's not allowed."And that's In The News. I'm Mario Ritter.更多听力请访问51voa.com