Tehran, Iran ? The head of the U.N. atomic watchdog agency told a 35-nation meeting Monday he had made little progress in his probe of suspicious aspects of Iran’s nuclear program.

The International Atomic Energy Agency “has not made much progress in resolving outstanding verification issues,” Mohamed ElBaradei told board member nations, alluding to suspicions that some of Tehran’s nuclear activities could be used to develop bombs.

The United States and Europe are lobbying other nations at the meeting to join them in urging Iran to accept a package of rewards for freezing uranium enrichment – and in warning Tehran of U.N. Security Council action if it refuses, according to documents shared with The Associated Press.

Chief U.S. delegate Gregory L. Schulte called on Iran to respond positively to demands that it negotiate and suspend enrichment, a process that can make nuclear fuel for a power plant or fissile material for an atomic bomb.