The International Atomic Energy Agency's (IAEA) board of governors on Wednesday approved a new four-year term for the agency's Director General Yukiya Amano, diplomats said.

The 65-year-old Japanese diplomat will start his second term in December following approvals from all IAEA members in September. Normally, Director General approved by the board of governors would be approved unanimously.

In Amano's second term, Iran's nuclear issue is expected to be his greatest challenge, after he and his team have failed to make any substantial breakthrough over the so called "structured approach" to resolving the outstanding issues on the possible military dimensions of Iran's disputed nuclear program.

Western countries fear Iran is enriching uranium to develop the capacity to build nuclear weapons. But Iran says the program is legitimate and intended for purely peaceful purposes.

The IAEA has been trying for more than a year to persuade Iran to give the agency the access it says it needs for its investigation, so far without progress.