It was Zawahiri.
* * *
https://en.wikipedia.org/wiki/Alexander_Litvinenko
Alleged Russia–al-Qaeda connection
In a July 2005 interview with the Polish newspaper Rzeczpospolita, Litvinenko alleged that Ayman al-Zawahiri, a prominent leader of al-Qaeda, was trained for half a year by the FSB in Dagestan in 1997.[49][67] Litvinenko said that after this training, al-Zawahiri “was transferred to Afghanistan, where he had never been before and where, following the recommendation of his Lubyanka chiefs, he at once ... penetrated the milieu of Osama bin Laden and soon became his assistant in Al Qaeda.”[68] Konstantin Preobrazhenskiy, a former KGB officer and writer, supported this claim and said that Litvinenko “was responsible for securing the secrecy of Al-Zawahiri’s arrival in Russia; he was trained by FSB instructors in Dagestan, Northern Caucasus, in 1996–1997.”[69] He said: “At that time, Litvinenko was the Head of the Subdivision for Internationally Wanted Terrorists of the First Department of the Operative-Inquiry Directorate of the FSB Anti-Terrorist Department. He was ordered to undertake the delicate mission of securing Al-Zawahiri from unintentional disclosure by the Russian police. Though Al-Zawahiri had been brought to Russia by the FSB using a false passport, it was still possible for the police to learn about his arrival and report to Moscow for verification. Such a process could disclose Al-Zawahiri as an FSB collaborator. In order to prevent this, Litvinenko visited a group of highly placed police officers to notify them in advance.” According to Sergei Ignatchenko, an FSB spokesman, al-Zawahiri was arrested by Russian authorities in Dagestan in December 1996 and released in May 1997.[70]
This article summarizes the details and debate on that:
https://www.businessinsider.com/exploring-al-qaedas-murky-connection-to-russian-intelligence-2014-6
Thanks