TEHRAN (AFP) - Iranian President Mahmoud Ahmadinejad insisted on Wednesday that Tehran has no plans to build a nuclear bomb, in a speech on the eve of its annual national atomic energy day. Addressing a large gathering in the central city of Isfahan where Iran has a uranium conversion facility, Ahmadinejad referred to US President Barack Obama as saying Iran has no right to have an atomic bomb. Recently, you (Obama) said that Iran can have nuclear technology for peaceful purpose, but does not have the right to have a bomb, Ahmadinejad said. I am telling you that the Iranian nation was never seeking a bomb as the era of bombs and armies is over, he said as the crowd cheered with chants of Death to America. Since taking office, Obama has made a series of diplomatic overtures towards Iran and last month on the Persian New Year, in a message to the Iranian people, he called for a new beginning in ties between Washington and Tehran. On Monday, however, he warned that Iran had to make a choice between having a nuclear weapon and building a better future for its people. Ahmadinejad said Iran was still waiting for fundamental and real changes from Obama and the US, with whom Tehran has had no diplomatic ties for three decades. If you are talking of change ... bismillah (In the name of God) ... change your method, your vocabulary and the path towards Iran, the Iranian leader said. You have extended your hand to us. If you are sincere in it, we welcome it, but if not, then our reply will be same as the one we gave to Mr (George W) Bush. On Thursday (today), Iran is to mark its national atomic energy day in Isfahan where Ahmadinejad is expected to make a key announcement. Meanwhile, the US and five other key world powers are to invite Iran for direct talks on its nuclear plans and other issues, they said in a joint statement in London on Wednesday. EU foreign policy chief Javier Solana will be tasked with extending the invitation to Tehran, said the statement by the US, China, France, Germany, Russia, Britain and the European Union. We strongly urge Iran to take advantage of this opportunity to engage seriously with all of us in a spirit of mutual respect, they said after talks in London. To that end, we shall ask (Solana) to extend an invitation to the Iranian Government to meet representatives of the E3+3, so that together we may find a diplomatic solution to this critical issue, they said. They added: We reaffirm our unity of purpose and collective determination through direct diplomacy to resolve our shared concerns about Irans nuclear programme, in line with the package proposals for cooperation with Iran. Meanwhile, the US voiced hope that Iran would accept the invitation on ending its nuclear program, saying it was ready to negotiate with mutual respect. State Department spokesman Robert Wood confirmed that the US would take part in any talks with Iran, an arch US foe since its 1979 Islamic Revolution. A diplomatic solution necessitates a willingness to engage directly with each other on the basis of mutual respect and mutual interests, and we hope that the government of Iran chooses to reciprocate, Wood told reporters. If Iran accepts, we hope this will be the occasion to seriously engage Iran on how to break the logjam of recent years and work in a cooperative manner to resolve the outstanding international concerns about its nuclear program.