ALMATY, Kazakhstan — World powers, fearful of scuttling negotiations beginning this week with Iran, are offering the Islamic republic some small new sanctions relief in return for curbing its nuclear program. But officials warned Monday that it’s unlikely that any compromise will be reached soon.

Negotiators set low expectations for the latest round of high-level diplomatic talks to begin Tuesday in Kazakhstan’s largest city — the first since last June’s meeting in Moscow that threatened to derail delicate efforts to convince Iran to stop enriching uranium to a level close to that used for nuclear warheads.

The stakes couldn’t be higher: the Obama administration is pushing for diplomacy to solve the impasse but has not ruled out the possibility of military intervention in Iran to prevent it from acquiring a nuclear weapon. And Israel has threatened it will use all means to stop Iran from being able to building a bomb, potentially as soon as this summer, raising the specter of a possible Mideast war.

Tehran maintains it is enriching uranium only to make reactor fuel and medical isotopes, and insists it has a right to do so under international law. It has signaled it does not intend to stop, despite harsh international sanctions on its oil and financial sectors, and U.N. nuclear inspectors last week confirmed Iran has begun a major upgrade of its program at the country’s main uranium enrichment site.

The clerical regime’s refusal frustrates the international community, which has responded by slapping Iran with a host of economic sanctions that U.S. officials said have, among other things, cut the nation’s daily oil output by 1 million barrels and slashed its employment rate. But, in a twist, negotiators now hope that easing some of the sanctions will make Tehran more agreeable to halting production of 20 percent enriched uranium — the highest grade of enrichment that Iran has acknowledged and one that experts say could be turned into warhead grade in a matter of months.

Negotiators from the six world powers — United States, Russia, China, Britain, France and Germany — also want Iran to suspend enrichment in its underground Fordo nuclear facility, and to ship its stockpile of high-grade uranium out of the country.

“What’s important to us is that they engage in these negotiations and take seriously what we’ve put on the table,” said Michael Mann, spokesman for EU foreign policy chief Catherine Ashton, who is leading the negotiations.

“No one is expecting everyone to walk out of here with a deal, but if we can have some forward momentum and they can show a willingness to take a confidence-building step, that’s very important,” Mann told reporters on Monday. He described the world powers’ newest gambit as “a good offer” but declined to say what it would include.