( CNN ) -- Iran is not cooperating , making it difficult for the UN 's nuclear watchdog agency to provide `` credible assurance '' that the country does n't possess undeclared nuclear material , the International Atomic Energy Agency Director General Yukiya Amano said Monday . Speaking to the IAEA 's board of governors , Amano said Iran should grant access `` without further delay '' to the Parchin military complex , where the Islamic Republic is believed to have tested rockets . Since Iran has not provided such access to date , `` The Agency therefore can not conclude that all nuclear material in Iran is in peaceful activities , '' Amano said . For about a decade , international observers have accused Iran of secretly pursuing a nuclear weapons program , which Iran consistently denies . Amano noted that Iran has recently begun installing IR-2m centrifuges at its fuel enrichment plant at Natanz , and that those high-speed devices that rotate to enrich uranium are more advanced than the previously-installed centrifuges . The IAEA board has been trying to negotiate cooperation from Iran for years . On Wednesday , diplomats from the so-called P5+1 -- the six-nation diplomatic bloc consisting of the United States , France , Britain , Germany , China and Russia -- held secretive talks with Iranian representatives in Kazakhstan , and then announced future meetings on March 18 and April 5 . The Islamic Republic already faces sanctions from the United Nations Security Council for violating a U.N. resolution forbidding it from enriching uranium . But Iran says since it signed the Nuclear Non-Proliferation Treaty , it should be able to enrich uranium for peaceful energy needs . The IAEA was created in 1957 to promote `` safe , secure and peaceful nuclear technologies , '' its website says . Among its endeavors , the agency tries to verify that countries correctly and completely account for their nuclear material and activities . The agency says as of December 31 , it had `` safeguards agreements in force '' with 179 official countries , and Taiwan . CNN 's Jennifer Deaton and Ivan Watson contributed to this report .
IAEA says Iran is not allowing proper inspections of its nuclear program . The agency has said it will continue to monitor Iran's compliance with the deal until a final agreement is reached. Iran has rebuffed IAEA requests for years . Several diplomats met with Iranians last week ; more meetings scheduled over next 5 weeks .