al-Nusra Front Syria
al-Qaeda affiliate Jabhat al-Nusra, or Nusra Front, in Syria Rami Al-Sayed/ AFP/Getty Images

A 31-year old woman who was captured by Al Qaeda militants in Syria seven months ago have finally released her after finding out that she has a long history of mental illness.

Sky News said that the woman managed to secretly contact a lawyer in London on a mobile phone using a WhatsApp voice message to Tasnime Akunjee, a lawyer who represented the families of three schoolgirls who had fled to Syria to join the Islamic State.

The Nusra Front, the group's Syrian branch agreed to free the woman from east London after receiving evidence that she had a long history of mental illness.

Akunjee said that although the militant group was "entirely reasonable" during the talks, he warned that other groups like the Isis would be far less likely to negotiate over the safe return of Britons who travelled to these areas to fight with them.

According to Sky News, no ransom was paid and her release was secured after two weeks of negotiations.

The Foreign Office is now providing consular assistance to the unidentified British woman, who has since been reunited with her brother and is now travelling through Turkey.