Aguilera posted a series of tweets -- along with an old photo of herself and Britney -- Monday night. Xtina started in saying, "These past few days I’ve been thinking about Britney and everything she is going through. It is unacceptable that any woman, or human, wanting to be in control of their own destiny might not be allowed to live life as they wish."

The singer then spoke to the allegations Britney made last week in claiming she was unable to get married or have children under the conservatorship, saying, "Every woman must have the right to her own body, her own reproductive system, her own privacy, her own space, her own healing and her own happiness."

Aguilera continued, "The conviction and desperation of this plea for freedom leads me to believe that this person I once knew has been living without compassion or decency from those in control."

Xtina's message of support comes nearly one week after Britney's stunning court testimony in which she told a judge she wanted out of a 13-year conservatorship without getting a mental evaluation.

In her statement Monday, Christina gave a nod to her former friendship with Britney, saying it was clear the woman she once knew has not been given the compassion she deserves.