Israeli Defence Minister Ehud Barak urged world powers not to waver in Wednesday's key talks with Iran, warning that any failure to halt enrichment would see Tehran obtain a nuclear weapon.

"In Baghdad, we must watch out that partial concessions do not allow Iran to avoid a tightening of sanctions," he said, as a second round of talks between Tehran and six world powers got underway in the Iraqi capital.

"Without strengthening the current painful sanctions, Iran will continue towards a nuclear capability," the defence minister told Israel's public radio.

"We must not blink, give up or capitulate until the very last minute," he said.

"If they let them continue, Iran will keep on enriching uranium from 20 percent to 60 percent and 90 percent and they really will get a nuclear weapon. I don't know exactly when but it will happen," he warned.

"Now is the time for the entire world to stop them," said Barak.

The so-called P5+1 grouping of diplomats from permanent UN Security Council members Britain, China, France, Russia and the United States plus Germany held a first round of talks with Iran on April 14 in Istanbul.

A day ahead of the second round, UN nuclear watchdog chief Yukiya Amano said his agency was poised to ink a deal with Tehran.

His comments were greeted with deep suspicion by Israel, which sees Iran's willingness to talk as a ploy to win an easing of sanctions and to gain more time for enrichment.

The world powers are hoping to secure Iran's agreement to suspend 20 percent enrichment and to ship its stockpiles of enriched uranium abroad.

But Israel has poured scorn on the P5+1 talks, with Barak deriding its demands of Tehran as "minimalist" and saying they would never be enough to make Iran halt its nuclear programme.

"If we set the bar too low, there is a danger that they will get most, if not all of what they want, and the Iranian nuclear programme will continue," he said.

Anything less than a demand to stop enriching uranium to 20 percent and to 3.5 percent, to remove all enriched uranium outside of the country, and to close down the Fordo plant near the holy city of Qom, was not enough, he said.

"The Iranians are continuing their game of chess in order to achieve nuclear weapons," he said, adding the customary warning: that "all options remain on the table" -- a reference to a possible pre-emptive military strike, which Israel has refused to rule out.

Later Wednesday, Strategic Affairs Minister Moshe Yaalon articulated the Israeli warning.

"The sanctions must continue and tighten, alongside international seclusion, support of the opposition and a reliable military option," he wrote on his Twitter account.

"If all this does not help, someone might have to instigate a military move against Iran," he warned, without noting who or how.

Earlier this year, Yaalon -- who served as Israel's military chief -- warned that no Iranian facility, however reinforced, is immune to Israeli attack.

The West and Israel, widely considered the Middle East's sole if undeclared nuclear power, suspect Iran is using its nuclear programme to build atomic weapons, charges that Tehran denies.

P5+1 making proposals 'of interest to Iran': EU
Baghdad (AFP) May 23, 2012 - World powers laid out on Wednesday a new package of proposals in crunch talks over Iran's nuclear programme which will be "of interest" to Tehran, a spokesman for the EU's foreign policy chief said.

"I am not going to go into the details of what we are proposing but of course we are putting proposals on the table that are also of interest to Iran," Michael Mann, spokesman for Catherine Ashton, told reporters at the talks in Baghdad.

"We have put a new offer on the table which addresses our main concerns to do with the Iranian nuclear programme," Mann said.

"We hope the Iranians will come back with a positive reaction to our proposals to deal with the concerns of the international community and to meet their international obligations under UN Security Council resolutions and the IAEA's findings ... There are things we can do for Iran."

After Ashton lays out the proposals hammered out in Amman on Tuesday by the P5+1 -- the United States, Russia, China, Britain, France and Germany -- the Iranians would then be given the floor to respond, he said.

Media reports said the package included a revival of previous attempts at a deal whereby Iran would ship abroad its stockpiles of enriched uranium in return for fuel for a reactor producing medical isotopes.

In return the P5+1 are expected to demand that Iran suspend what they see as the most worrying part of Tehran's nuclear programme, namely the enrichment of uranium to purities of 20 percent.

Uranium enriched at lower levels of around three percent can be used in power generation -- Iran currently has one atomic power plant -- or at 20 percent to produce medical isotopes, used to diagnose cancers and other diseases.

But the capability to enrich to 20 percent has raised fears in much of the international community that Iran could also begin to enrich to 90 percent purities -- the level needed for the fissile core of a nuclear weapon.

"Obviously, the ball is in their court now. We have a number of things that we want them to do. Obviously the enrichment of uranium to 20 percent is one of the major things that the international community is worried about," Mann told Al-Jazeera in an interview.

The media reports, described by one P5+1 diplomat as "pretty spot on", said the world powers would however not offer to relax existing sanctions or postpone other restrictions due to come into force, as Iran wants.

Instead, Iran could be given a pledge of no new sanctions, easier access to aircraft parts and a possible suspension of an EU insurance ban on ships carrying Iranian oil.

"This is the second meeting. Istanbul kicked off the process (in mid-April) of discussions. Now we're getting on to the real substance of the matter," Mann said.

"This is a process, you are not going to get dramatic happenings today, I don't think. We are going to make solid progress if things go well," he said.

"It has never been the intention that today would be the end of negotiations. Today is part of a process. We are keen to get a move on but these things can't be solved overnight."