A top US official says Myanmar must grant "unhindered access" to cyclone-devastated areas as a condition for receiving more American aid. US Deputy Assistant Secretary of State Scot Marciel told an international donors conference in Myanmar that the US is prepared to offer significant aid for cyclone survivors - if the junta allows foreign experts to assess the affected areas. He told the Sunday conference the United States has already provided more than $20.5 million in aid. Cyclone Nargis struck three weeks ago. Myanmar's ruling generals told the United Nations on Friday they were now willing to allow foreign aid workers into the devastated Irrawaddy delta.