The White House has confirmed that an American Islamic State (Isis) hostage, 26-year-old aid worker Kayla Jean Mueller, has died.

"It is with profound sadness that we have learned of the death of Kayla Jean Mueller," Obama said in a statement. "I convey our deepest condolences."

Several Isis-linked Twitter accounts have claimed that the American aid worker was killed in the bombing raid on the Syrian city of Raqqa early in Friday (February 6).

"Isis is a hateful and abhorrent terrorist group whose actions stand in stark contrast to the spirit of people like Kayla," reads the statement.

The Mueller family also released a statement confirming the death of their daughter.

"We are heartbroken to share that we've received confirmation that Kayla Jean Mueller has lost her life," her parents and brother said on Tuesday.

"Kayla was a compassionate and devoted humanitarian. She dedicated the whole of her young life to helping those in need of freedom, justice, and peace."

According to reports, IS sent the Mueller family an email with a picture telling them that the woman was dead. The US intelligence community then verified the photo.

Mueller family also released a letter that Kayla wrote when she was captive in 2014.

Here is the statement from the White House:

"It is with profound sadness that we have learned of the death of Kayla Jean Mueller. On behalf of the American people, Michelle and I convey our deepest condolences to Kayla's family – her parents, Marsha and Carl, and her brother Eric and his family – and all of those who loved Kayla dearly. At this time of unimaginable suffering, the country shares in their grief.

Kayla dedicated her life to helping others in need at home and around the world. In Prescott, Arizona, she volunteered at a women's shelter and worked at an HIV/AIDS clinic. She worked with humanitarian organizations in India, Israel, and the Palestinian territories, compelled by her desire to serve others. Eventually, her path took her to Turkey, where she helped provide comfort and support to Syrian refugees forced to flee their homes during the war. Kayla's compassion and dedication to assisting those in need shows us that even amongst unconscionable evil, the essential decency of humanity can live on.

Kayla represents what is best about America, and expressed her deep pride in the freedoms that we Americans enjoy, and that so many others strive for around the world. She said: "Here we are. Free to speak out without fear of being killed, blessed to be protected by the same law we are subjected to, free to see our families as we please, free to cross borders and free to disagree. We have many people to thank for these freedoms and I see it as an injustice not to use them to their fullest."

Kayla Mueller used these freedoms she so cherished to improve the lives of others. In how she lived her life, she epitomized all that is good in our world. She has been taken from us, but her legacy endures, inspiring all those who fight, each in their own way, for what is just and what is decent. No matter how long it takes, the United States will find and bring to justice the terrorists who are responsible for Kayla's captivity and death.

ISIL is a hateful and abhorrent terrorist group whose actions stand in stark contrast to the spirit of people like Kayla. On this day, we take comfort in the fact that the future belongs not to those who destroy, but rather to the irrepressible force of human goodness that Kayla Mueller shall forever represent."