The incident happened on July 25 when the advocate identified as Lalji Verma and two of his aides barged into the victim's house and gangraped her, Station House officer of Kotwali, Amethi, Mohammad Hamid said.
There was a land dispute going on between the accused and the victim, he said.
On the basis of the complaint by the married woman, an FIR under relevant sections of the IPC has been registered against the accused who are absconding, police said.
The woman was sent for medical examination and the matter is being investigated, the SHO said.