Japan urged Iran on Tuesday to stick to a 2015 nuclear deal with world powers, expressing its strong concern over Tehran's recent decision not to adhere to its limits.

"Iran's latest announcement is disappointing and leaves us strongly concerned," Chief Cabinet Secretary Yoshihide Suga said at a regular news conference in Tokyo.

"We ask Iran to return to (observing) its commitments under the agreement immediately and cooperate fully with the International Atomic Energy Agency," he said.