VIENNA (AFP) - World powers urged Iran to cooperate with the UN atomic watchdog Wednesday, otherwise it could soon face further censure for blocking the investigation into its controversial nuclear drive. "We call on Iran to cooperate fully with the (International Atomic Energy) Agency," the so-called P5+1 grouping said in their first joint statement to the IAEA's board of governors in two years. The P5+1 comprises the five permanent members of the UN Security Council - Britain, China, France, Russia, the United States - plus Germany. It is talking with the Islamic republic to allay fears over its nuclear programme, which Tehran insists is entirely peaceful, but which the West believes masks a covert weapons programme. The last time the six powers issued a joint statement to the IAEA's 35-member board of governors was in March 2009. Since then, the group has held two rounds of talks with Tehran, in Geneva in December and in Istanbul in January, but which produced no concrete breakthrough in the long-running standoff. "We came to Geneva and Istanbul with a constructive spirit and proposed in Istanbul several practical ideas aimed at building confidence and to facilitate the engagement of a constructive dialogue with Iran on the basis of reciprocity and step-by-step approach," said Russian governor Grigory Berdennikov on behalf of the P5+1 at an ongoing IAEA meeting at its Vienna headquarters. While no "substantive result" was reached in Istanbul, "we look to Iran to engage in future in a similarly constructive spirit," Berdennikov said. "We remain ready to participate actively in the process with Iran. We expect Iran to demonstrate a pragmatic attitude and to respond positively to our proposal and to our openness toward dialogue and negotiations. The door remains open," he said. On Monday, IAEA director general Yukiya Amano had complained that Iran was "not providing the necessary cooperation" and, in particular, was stonewalling questions about alleged weaponsiation studies. In a statement on behalf of the 27-nation EU, Hungary expressed "serious concern" about Iran's refusal the so-called "alleged studies" since August 2008. Hungary suggested that "it might be helpful if (Amano) could provide the board with a comprehensive analysis on possible military dimensions to Iran's nuclear programme." In his latest report on Iran, the director general had revealed that the IAEA was in possession of "new information" that the weaponisation work - including uranium conversion, high explosives testing and the adaptation of a ballistic missile cone to carry a nuclear warhead - may have gone on beyond 2004, which is more recently than initially thought. Meanwhile, the United States believes Iran intends to get to the brink of a nuclear arms capability so it could make them if it wished, a senior US official said Wednesday. However, Robert Einhorn, the US State Department's senior adviser for nonproliferation and arms control, said, he does not believe Iran soon plans to attempt a nuclear "breakout" - abandoning its commitments under the Nuclear Non-Proliferation Treaty and moving full-speed to toward atomic weapons.