WASHINGTON (Reuters) - U.S. President Barack Obamas adviser on arms control said on Friday Iran could face fresh international sanctions after talks in Switzerland this week at which Tehran refused to discuss uranium enrichment. In the wake of the Geneva talks, we and our allies are determined to maintain and even increase pressure, said Gary Samore, White House coordinator for arms control and weapons of mass destruction counter-terrorism. We need to send the message to Iran that sanctions will only increase if Iran avoids serious negotiations and will not be lifted until our concerns are fully addressed, he told an event in Washington on Iran. Iran rejects Western suspicions that its nuclear program is a cover for acquiring an atomic bomb. Enriched uranium can be used both in power stations and, when refined to a much higher degree, in nuclear bombs. Repeated U.N. Security Council resolutions demand Iran suspend enrichment and allow tougher U.N. inspections of its atomic work as a way of convincing the world it is not secretly trying to develop a nuclear weapons capability. As we continue to keep the door open for diplomacy, we will continue to ratchet up pressure, a senior administration official separately said. Iran has a choice, address international concerns and live up to its obligations or face increasing isolation.