DUBAI (Reuters) - Iran demanded on Monday the removal of all sanctions in a verifiable process as talks resumed between Tehran and world powers that are aimed at reinstating a 2015 nuclear pact abandoned by Washington three years ago.

       In a statement published just before the talks started, Iran's Foreign Minister Hossein Amirabdollahian said: "The United States still fails to properly understand the fact that there is no way to return to the deal without verifiable and effective lifting of all sanctions imposed on the Iranian nation after the U.S. departure."

       "The return of the U.S. to the nuclear deal would be meaningless without guarantees to prevent the recurrence of the bitter experience of the past," he said, adding that "this opportunity is not a window that can remain open forever".

       (Writing by Parisa Hafezi; Editing by Gareth Jones)