A British woman fighting with a Kurdish armed unit has died in Syria, her father has said.
Anna Campbell, from Lewes, East Sussex, died on March 15 in Afrin while with the Kurdish Women's Protection Units, the YPJ, the BBC said.
It is feared she was killed by Turkish air strikes.
Ms Campbell is the first British woman to have been killed in Syria with the YPG or YPJ. Seven men have died in the country while fighting alongside the groups.
Ms Campbell's father, Dirk, told the broadcaster the 26-year-old "wanted to create a better world and she would do everything in her power to do that".
He added: "I told her of course that she was putting her life in danger, which she knew full well she was doing. I feel I should have done more to persuade her to come back, but she was completely adamant."
The YPJ is an all-female brigade of the Kurdish People's Protection Units YPG, which has around 50,000 Kurdish men and women fighting against IS in northern Syria.
Mr Campbell told the BBC he understands his daughter joined her Kurdish comrades when they left the fight against IS to defend Afrin from Turkish forces.
In a statement to The Guardian, YPJ commander and spokeswoman Nesrin Abdullah said Ms Campbell's death was a "great loss".
She told the paper: "Campbell's martyrdom is a great loss to us because with her international soul, her revolutionary spirit, which demonstrated the power of women, she expressed her will in all her actions.
"On behalf of the Women's Defence Units YPJ, we express our deepest condolences to (her) family and we promise to follow the path she took up. We will represent her in the entirety of our struggles."
Conflict between Turkey and Kurdish groups has been inflamed since January.
Over the weekend, Turkey's president Recep Tayyip Erdogan said the country's military had captured the town centre of Afrin, which was previously controlled by the YPG.
Nearly two months after launching an offensive on the Kurdish territory, he announced that the Turkish flag and that of Syrian opposition fighters had been raised in the town.