There have been many reports about relations between Iran and the al-Qaeda senior leadership, especially on exchanging prisoners. However, it appears that new leaked documents are proving this with facts, Al Arabiya.net reported.
Asharq Al Awsat published documents of bin Laden showing close relations between al-Qaeda and Iranian leadership in the 1990s.
Documents obtained by the US following the 2011 assassination of bin Laden in Pakistan show al-Qaeda elements being very active in Iran.
Al-Qaeda in 2006 was seeking to open an office in Tehran, yet the skyrocketing price of opening such an office at that time prevented such a step, according to these documents.
Relations between Iran and al-Qaeda go back to the 1990s when this group was stationed in Sudan, since Tehran and Khartoum enjoyed warm relations at the time.
 

The US Treasury Department freezing the assets of six al-Qaeda leaders shows Tehran was an important element in providing money to al-Qaeda in Pakistan and Afghanistan.
These documents also reveal that despite the relations between the two sides, bin Laden was always very careful about Iran and warned his followers about the fact that Iran may probably be spying on their group.
In a letter bin Laden wrote to his wife, the former al-Qaeda leader had forecasted Iran will spy on his family after they left Tehran. He had thus suggested to his family members to leave everything behind.