Dr Izzat Atiya of Egypt's al-Azhar University said it offered a way around segregation of the sexes at work.
His fatwa stated the act would make the man symbolically related to the woman and preclude any sexual relations.
The president of al-Azhar denounced the fatwa, which Dr Atiya has since retracted, as defamatory to Islam.
According to Islamic tradition, or Hadith, breast-feeding establishes a degree of maternal relation, even if a woman nurses a child who is not biologically hers.
'Family bond'
In his fatwa, Dr Atiya, the head of al-Azhar's Department of Hadith, said such teachings could equally apply to adults.
He said that if a woman fed a male colleague "directly from her breast" at least five times they would establish a family bond and thus be allowed to be alone together at work.
"Breast feeding an adult puts an end to the problem of the private meeting, and does not ban marriage," he ruled.
"A woman at work can take off the veil or reveal her hair in front of someone whom she breastfed."
The legal ruling sparked outrage throughout Egypt and the Arab world.
On Sunday, Dr Atiya retracted it, saying it had been the result of a "bad interpretation of a particular case" during the time of the Prophet Muhammad.
Egypt's minister of religious affairs, Mahmoud Zaqzouq, has called for future fatwas to "be compatible with logic and human nature".
An Islamic cleric named Ezzat Atiya issued a '''' to get around  and ''hijab'' in Islam.  He stated that ''symbolic'' breastfeeding could be used to make it permissible for male and female colleagues to work together alone.

Dr. Atiyah had stated that the breastfeeding does not have to be by the woman herself.  "This can also be achieved by means of the man's mother or sister suckling the woman, or by means of the woman's mother or sister suckling the man" he wrote.

Atiya works at the Al-Azhar University, an Islamic seminary in Egypt.  The seminary was established by a Shi'a  and is named after .  Zahra was the wife of .  Al-Azhar University has a fatwa that officially sanctioned  with one condition only: martyrdom operations are only allowed in Israel.  The university has had this ruling for a long time and has stood by it.  

Atiyah had said, 

According to , "If someone tells you he has a new interpretation of Islam, sock him in the mouth."