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

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