A U.N. nuclear team on Wednesday announced plans to revisit Tehran "in the very near future," indicating some progress on its quest to wrest information from Iran about allegations that it secretly worked on an atomic arms program.

The announcement from mission leader Herman Nackaerts came shortly after his team landed at Vienna airport and on the heels of three days of discussions with Iranian officials.

While Nackaerts gave no details on what the International Atomic Energy Agency experts had achieved, diplomats had said before their departure that their main focus was to break Iranian resistance to talking about the weapons program allegations.

"We had three days of intensive discussions about all our priorities, and we are committed to resolve all the outstanding issues," Nackaerts told reporters. "And the Iranians said the are committed, too.

"But of course there's still a lot of work to be done," he said. "So we have planned another trip in the very near future."

Any progress on the issue would be significant. Iran has refused to discuss the alleged weapons experiments for more than three years, saying they are based on "fabricated documents" provided by a "few arrogant countries" -- a phrase authorities in Iran often use to refer to the United States and its allies.

The IAEA team was seeking progress on its efforts to talk to key Iranian scientists suspected of working on a weapons program. They also hoped to break down opposition to their plans to inspect documents related to nuclear work and secure commitments from Iranian authorities to allow future visits.

Beyond concerns about the purported weapons work, The United States and its allies want Iran to halt uranium enrichment, which they worry could eventually lead to weapons-grade material and the production of nuclear weapons. Iran says its program is for peaceful purposes -- generating electricity and producing medical radioisotopes to treat cancer patients.

Tehran is under four sets of U.N. Security Council sanctions because of its refusal to heed international concerns about its nuclear programs, as well as penalties imposed by the United States and Western nations meant to force it into dialogue