Iran’s top nuclear negotiator has said a proposal put forward EU foreign policy chief Javier Solana to end a nuclear standoff has positive points but also contains some “ambiguities” that need to be removed.The document includes a range of initiatives and penalties aimed at convincing Tehran to halt making nuclear fuel. Ali Larijani said they had held constructive talks and he hoped they would achieve a balanced and logical conclusion. But Iran remains adamant it won’t give up uranium enrichment. It denies Western claims it is trying to produce an atomic bomb and says it needs nuclear fuel to meet its electricity needs. The initiative, put together by France, Britain and Germany, has been approved by the United States, China and Russia. It is thought to include incentives such as proposals to give Iran nuclear reactor technology and the opportunity to purchase aircraft parts from Boeing and Airbus. Possible penalties could take the shape of an arms embargo.