The United States and Iran are due to hold their second round of nuclear talks on Saturday, as what both sides are looking for in a deal begins to take shape.

U.S. talks that were supposed to take place on Wednesday will be shifted to Saturday, Tehran's foreign ministry spokesperson said, with a third round of high-level nuclear talks due on the same day in Oman.

Negotiations between Iran and the United States over Tehran’s rapidly advancing nuclear program will move to what’s known as the “expert level” — a sign analysts say shows that the talks are moving forward rapidly.