"At present, there is some uncertainty about the prospects of negotiations going into the future, but we are already seeing a light at the end of the tunnel. Negotiations have entered a critical stage," Wang said on the sidelines of the annual National People's Congress.
The diplomat noted that reaching a long-awaited comprehensive deal would be crucial in promoting nuclear nonproliferation, peace and stability on the world stage.
The group of international mediators, collectively referred to as Iran and P5+1, are tasked with ensuring Tehran's civilian nuclear program does not contain plans of developing nuclear weapons.
On Saturday, French, British, German and US counterparts met in Paris, where the diplomats indicated certain progress in the state of negotiations over Iran's nuclear program despite disparities that must be worked out.
The deadline for reaching an all-encompassing deal is set for July 2015. The agreement is expected to ensure the peaceful nature of Iran's nuclear program in exchange for the lifting of sanctions.