Iran signaled on Tuesday that it had made further advances in the country’s disputed nuclear energy program, announcing that President Mahmoud Ahmadinejad would reveal “key nuclear achievements” on Wednesday. An Iranian news agency said he was likely to proclaim that a new uranium enrichment plant built inside a mountain near the holy city of Qum was “fully operational.”

The announcement appeared timed to convey the defiant message that the increasingly harsh Western economic sanctions imposed on Iran were having no effect on the government’s determination to proceed with its nuclear program. The United States, Europe and Israel have all called the program a cover for Iranian efforts to develop nuclear weapons capability, an accusation that Iran denies.

The new uranium enrichment plant, known as Fordo, has raised Western concerns because it is buried deep underground, making it more impervious to scrutiny. The Fordo plant also has elevated distrust of Iran because the plant’s construction had been kept a secret until Western intelligence confirmation of its existence forced the Iranians to acknowledge the plant in September 2009, just as President Obama and European allies were announcing it. The Iranians said at the time that they had always intended to reveal the plant’s existence.

Last month, inspectors from the International Atomic Energy Agency, the United Nations nuclear watchdog, confirmed that Iran had started uranium enrichment at Fordo.