Vienna: Tehran has agreed to address by August 25 some issues related to a long-stalled investigation by the International Atomic Energy Agency (IAEA) into suspected Iranian atomic bomb research, the UN International Atomic Energy Agency said on Wednesday.

In a potentially important step forward in the IAEA’s efforts to advance its inquiry, it said Iran would provide information “with respect to the allegations related to the initiation of high explosives, including the conduct of large-scale high-explosives experimentation in Iran”.

Iran would also provide “information and explanations related to studies made and/or papers published in Iran in relation to neutron transport and associated modelling and calculations and their alleged application to compressed materials”.

Both issues were part of a landmark report issued by the IAEA in 2011 that included a trove of intelligence information pointing to past tests and experiments in Iran that could be relevant for the development of nuclear weapons. Iran denies having worked on a nuclear weapons capability in any form.

How Iran responds to the IAEA’s questions is regarded as a litmus test of its readiness to start engaging with the investigation into what the UN agency calls the possible military dimensions of its nuclear programme.

US officials say it is vital for Iran to resolve the IAEA’s concerns if broader diplomatic efforts by Washington and five other world powers to resolve their decade-old nuclear dispute with Iran are to succeed.