VIENNA/PARIS — The United States, Britain, France and Germany are seeking a resolution by the U.N. nuclear watchdog's board next week reporting Iran to the U.N. Security Council for the first time in 20 years, according to diplomats and the proposed text seen by Reuters. If passed, the resolution would follow up on one adopted on June 12 of last year declaring Iran in breach of its non-proliferation obligations for not fully cooperating with an investigation into uranium traces found at undeclared sites. Israel started bombing Iran's nuclear facilities the next day, soon joined by the U.S. Iran's uranium-enrichment plants were destroyed or badly damaged. Iran has not let International Atomic Energy Agency inspectors return to the bombed sites since then or verify what remains of its stocks of enriched uranium, some of which was enriched to up to 60 percent purity, a short step from weapons grade. Fresh diplomatic escalation A resolution by the IAEA's 35-nation board reporting Iran to the Security Council would also be the culmination of a standoff over IAEA access to those sites, since