WASHINGTON In another significant shift from former President George W. Bush's policy of isolating Iran, the Obama administration said Wednesday it will participate directly in group talks with the Islamic Republic over its controversial nuclear programme. The United States will be at the table "from now on" when senior diplomats from the five permanent members of the U.N. Security Council and Germany meet with Iranian officials to discuss the nuclear issue, a State Department spokesman said. The Bush administration had generally shunned such meetings, although it attended one last year. "We believe that pursuing very careful engagement on a range of issues that affect our interests and the interests of the world with Iran makes sense," Secretary of State Hillary Rodham Clinton told reporters. "There is nothing more important than trying to convince Iran to cease its efforts to obtain a nuclear weapon." State Department spokesman Robert Wood said the decision was conveyed to representatives of Britain, China, France, Germany, Russia by the third-ranking U.S. diplomat William Burns at a Wednesday meeting in London. That group, known as the "P5+1," announced earlier that it would invite Iran to attend a new session aimed at breaking a deadlock in the talks. "The U.S. remains committed to the P5+1 process; what is different is that the U.S. will join P5+1 discussions with Iran from now on," Wood said, adding that Washington was hopeful Iran would attend. "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," he said. "Any breakthrough will be the result of the collective efforts of all the parties, including Iran." Wood said the administration wants a diplomatic resolution to the nuclear issue and believes that requires "a willingness to engage directly with each other on the basis of mutual respect and mutual interests." "We hope that the government of Iran chooses to reciprocate," he added. The invitation is to be sent to the Iranians by European Union foreign policy chief Javier Solana. In a statement the group said it welcomed the "new direction" of U.S. policy toward Iran. No time frame was given for a date of the meeting. Earlier, Iran's President Mahmoud Ahmadinejad said that his country welcomes talks with the United States should it prove to be "honest" in extending its hand toward Iran, one of the strongest signals yet that Tehran welcomes Obama's calls for dialogue. "The Iranian nation welcomes a hand extended to it should it really and truly be based on honesty, justice and respect," Ahmadinejad said in a speech broadcast live on state television. The United States and some of its allies accuse Iran of seeking to build a nuclear weapon, a claim that Iran denies. Tehran insists it has the right under the Nuclear Nonproliferation Treaty to develop reactor fuel using enrichment for civilian energy purposes. Through the negotiations, the P5+1 group has offered Iran a package of incentives to stop enriching and reprocessing uranium. Tehran has thus far rebuffed the offer despite the fact that its refusal has led to the imposition of three rounds of economic, trade and financial sanctions by the U.N. Security Council. Individual countries, led by the United States and members of the European Union, have also imposed their own sanctions on Iran. The United States and Iran have not had diplomatic relations since the 1979 Islamic Revolution and subsequent hostage taking at the U.S. Embassy in Tehran and official exchanges between the two nations have largely been limited to talks over security in Iraq and the situation in Afghanistan. Talks with Iran and Wednesday's step is the latest in a series of moves that the administration has taken to reach out to Iran. These initiatives have included inviting Tehran to an international meeting on Afghanistan late last month, at which U.S. officials in another break from Bush-era policy delivered a written message to Iranian diplomats politely asking for information about detained and missing Americans in the country. Also last month, President Barack Obama recorded a video addressed to the Iranian people, in which he said the U.S. is prepared to end years of strained relations.