Iran's production of highly enriched uranium continues and it has not improved cooperation with the U.N. nuclear watchdog despite a resolution demanding this at the agency's last board meeting, watchdog reports seen by Reuters showed on Thursday. Iran's stock of uranium in the form of uranium hexafluoride enriched to up to 60% purity, close to the roughly 90% of weapons grade, grew an estimated 22.6 kg to 164.7 kg, one of the two confidential quarterly International Atomic Energy Agency reports sent to member states said. According to an IAEA yardstick, that is 2 kg short of being enough, in theory, if enriched further, for four nuclear bombs.