In a rare show of unity, Iran and the world's major powers on Saturday welcomed their first nuclear meeting after a year of deadlock over Iran's nuclear talks, but analysts say there is still a long way to go before Teheran's nuclear issue is settled.

While no concrete deal was reached on Iran's uranium enrichment, both sides agreed to prepare a draft for discussion in the next round of talks, to be held in Baghdad on May 23.

The talks showed that the US and Iran have made more conciliatory gestures to each other, but the two countries are a long way from improving ties because of a lack of mutual trust, said Zhang Xiaodong, secretary-general of the China Association for Middle Eastern Studies.

"It is hard to call what happened on Saturday a breakthrough, as both sides need to make concrete gestures to establish confidence, and there's still much work to be done," Zhang said.

Iran's nuclear issue is complex and sensitive, and cannot be solved in one round of talks, said Assistant Foreign Minister Ma Zhaoxu, who led the Chinese delegation in the nuclear talks.

While there may be some bumps on the road ahead, related parties should build their confidence, stay patient, stick to negotiations and seek to bridge divisions through dialogue, he said.

Bruno Tertrais, a senior research fellow at the Foundation for Strategic Research in Paris, said if there were a breakthrough, it would come at the next meeting.

"It is only when both sides have agreed on the next steps ... and when whatever Iran will agree to can be verified, that we will be able to say for certain that something real has happened. Until then, it's only talk," he said.

The talks in Istanbul on Saturday saw the United States, Russia, China, Britain, France and Germany sitting at the same table with Iran. Knowing the road ahead is tough, both sides hailed the positive tone of the talks as a contrast to the previous round 14 months ago.

EU foreign policy chief Catherine Ashton, who formally led the talks on behalf of the six powers, called the meeting "constructive and useful".

She expressed the hope they will lead to "a sustained process of serious dialogue, where we can take urgent practical steps to build confidence and lead on to compliance by Iran with all its international obligations".

The White House welcomed the "positive attitude" by Iran and world powers the meeting - but Deputy National Security Adviser Ben Rhodes reiterated Washington's call for Teheran to take "concrete steps".

Iranian chief negotiator Saeed Jalili said the talks made "some progress", but he acknowledged "some points of difference".

"What we saw today in the talks was the interest of the other party in the talks and cooperation, which is considered positive," he said.

The last time Iran met with the six powers in Istanbul was in January 2011, but it quickly became apparent that the talks would go nowhere.

China Daily-AP-AFP