Iran has made it fully clear that its nuclear activities are peaceful, Posada said Tuesday in a meeting with Iranian Foreign Minister Mohammad Javad Zarif in Madrid.
Therefore, he added, the lifting of all anti-Iran sanctions will complete the process of nuclear talks between Tehran and the Group 5+1 (Russia, China, the US, Britain, France and Germany).
Iran and the Group 5+1, also known as P5+1 or E3+3, are in talks to hammer out a lasting accord that would end more than a decade of impasse over Tehran's civilian nuclear program.
On April 2, they reached a framework nuclear agreement after more than a week of intensive negotiations in Lausanne, Switzerland, with both sides committed to push for a final deal until the end of June.
Elsewhere in his remarks, Posada voiced Spain's willingness to promote parliamentary relations with the Islamic Republic and said a delegation of the Spanish MPs will travel to Tehran in the coming months.
Zarif, for his part, emphasized the importance of parliamentary diplomacy and said it will positively affect the relations between Tehran and Madrid.