Nuclear negotiations between Iran and six world powers have not ended yet, senior U.S. State Department official said on Sunday.

"We do not have a lid yet tonight," the official said.

Earlier an Iranian diplomat said the talks aimed at securing a suspension of parts of Iran's nuclear program in exchange for limited sanctions relief had ended. A Western diplomat told Reuters on condition of anonymity that a deal was likely.

U.S. Secretary of State John Kerry walks down the steps of his aircraft as he arrives at Geneva International airport November 23, 2013. Kerry arrived in Geneva on Saturday to join talks on Iran's contested nuclear program, as Tehran and six world powers appeared to be on the verge of a breakthrough in the decade-old dispute. [Photo/Agencies]