US Secretary of State John Kerry (L) meets with Iranian Foreign Minister Mohammad Javad Zarif on what is expected to be "implementation day," the day the International Atomic Energy Agency (IAEA) verifies that Iran has met all conditions under the nuclear deal, in Vienna January 16, 2016. [Photo/Agencies]

VIENNA -- Iranian Foreign Minister Mohammad Javad Zarif and US Secretary of State John Kerry on Saturday came together in Vienna to fix the final details for the implementation of comprehensive nuclear deal.

Differences between Iran and US over Tehran's long term uranium enrichment research plan still need to be resolved, a source told Xinhua on Saturday.

However, the gap could be bridged soon, not likely to kill the deal, the source said.

The International Atomic Energy Agency(IAEA) is expected to issue a report over Iran's compliance of the nuclear deal which would trigger the comprehensive relief of nuclear-related sanctions imposed on Tehran, Iran and EU are also expected to give a joint statement over the implementation of the deal.

"All oppressive sanctions imposed against Iran will be annulled today," Zarif told Iranian Media upon his arrival in Vienna earlier Saturday.

It is clear that both sides eye on the implementation of the deal as soon as possible after years of diplomatic effort.

Western states, especially the US, demand the "break out" time of Iran's atomic bomb to be over one year technically, so the western powers have enough time to react once the Tehran shows incompliance of the deal.

Under the deal reached in July last year, Iran agreed to significantly scale back its nuclear program in exchange for the sanction relief, while giving more transparency of its nuclear plan to address the concern of the western countries.

IAEA board members have decided to close the consideration of Iran's alleged nuclear weapon program in December last year as Tehran has cooperated with the agency to resolve the issue.