The United States, China, Russia, France and Britain reiterated their call Thursday for Iran to cooperate with the UN nuclear watchdog over its disputed nuclear programme.
"We remain concerned by Iran's persistent failure to comply with its obligations under UNSC (UN Security Council) resolutions and to meet the requirements of the IAEA Board of Governors Resolutions," the five powers said in a statement on the sidelines of a non-proliferation meeting in Vienna.
"We stress the need and urgency for Iran to reach an agreement with the IAEA on a structured approach, including on access to relevant sites and information... to resolve all outstanding issues, particularly those relating to possible military dimensions" of Tehran's nuclear programme," they added.
These demands were already spelled out in a resolution adopted by the board of the governors of the International Atomic Energy Agency (IAEA) in November, they noted.
The document was then approved by the 35-member board after an IAEA report said it had "credible" information that the Islamic republic was working on a nuclear bomb, something Tehran has consistently denied.
Thursday's statement by the five permanent UN Security Council members comes just as the IAEA has confirmed it will resume talks with Iran on May 14 and 15 in Vienna over the country's nuclear programme.
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Talks had been frozen since two IAEA visits to Iran in February, when the agency complained it was denied access to the Parchin military site near Tehran, where explosives testing for warhead research allegedly took place.
The West believes Iran is trying to develop an atomic bomb under cover of its civilian programme although Tehran insists the programme is solely peaceful.
Last month, the so-called P5+1 group -- the five Security Council members plus Germany -- met in Istanbul with Iran to discuss their concerns, with a further meeting set for May 23 in Baghdad.
On another hot nuclear topic, Thursday's statement urged North Korea to refrain from further nuclear moves, as fears mount that Pyongyang could soon conduct a third nuclear test, following earlier ones in 2006 and 2009.
On April 13, a much-vaunted missile launch to celebrate the 100th anniversary of North Korea's founding leader Kim Il-Sung misfired.
Nevertheless, the five powers expressed "serious concern" Thursday and called on Pyongyang to "refrain from further actions which may cause grave security concerns in the region, including any nuclear tests."
They also pushed the regime to reinitiate six-party talks that broke down in December 2008.