(Reuters) - The U.N. atomic agency says it needs an extra 4.6 million euros ($5.67 million) from member states to finance monitoring of an extended nuclear deal between Iran and six world powers, a document seen by Reuters said on Wednesday. Iran and the United States, France, Germany, Britain, China, and Russia failed to meet a Nov. 24 deadline for resolving a 12-year dispute over Tehran's nuclear program and gave themselves until the end of June 2015 for further negotiations. As a result, a preliminary agreement reached late last year, under which Iran halted its most sensitive nuclear activity in exchange for limited sanctions easing, will remain in force. The International Atomic Energy Agency (IAEA) - which has inspectors on the ground every day of the week - is tasked with checking that Iran meets its commitments under the accord. In a confidential note to member states ahead of an extraordinary IAEA board meeting next week to discuss the issue, the U.N. agency said it estimated the cost of its extended monitoring work at 5.5 million euros. A part of this would be covered internally and by earlier unspent contributions, but an additional 4.6 million euros "of voluntary extra budgetary contributions would be required". IAEA Director General Yukiya Amano "invites member states which are in a position to do so to make the necessary funding available for the continuation of the agency’s monitoring and verification" in Iran, it added. Because of the deal's political importance, diplomats have said there should be no problem raising the required funds. Iran denies Western allegations it has been seeking to develop the capability to make nuclear weapons. But its refusal to scale back its uranium enrichment program has drawn international sanctions hurting its oil-dependent economy The IAEA's workload has increased significantly under the interim accord. Inspectors now visit Iran's uranium enrichment facilities of Natanz and Fordow daily, compared to about once a week before. It has also procured and installed specialized equipment and carried out more analytical work. The agreement, designed to buy time for negotiations on a final settlement, was initially due to run for six months from January but first extended in July and again last week. The IAEA earlier this year asked for contributions of 6.5 million euros to cover its extra Iran-related costs. Amano last month said the IAEA's "verification effort in Iran has doubled".