Angelina Jolie has stepped down from the United Nations.

The 47-year-old actress had served on the U.N. High Commissioner of Refugees Special Envoy for more than 20 years but explained she had decided to quit so she can focus on work with those "directly affected" by conflict.

She said: "I am stepping down today from my work with the UN Refugee Agency. I believe in many things the UN does, particularly the lives it saves through emergency relief. UNHCR is full of amazing people making a difference to people’s lives every day. Refugees are the people I admire most in the world and I am dedicated to working with them for the rest of my life. I will be working now with organizations led by people most directly affected by conflict, that give the greatest voice to them."

The 'Mr. and Mrs. Smith' star - who has Maddox, 21, Pax, 18, Zahara, 17, Shiloh, 16, and 14-year-old twins Vivienne and Knox with her former spouse Brad Pitt - added that she was "grateful" for the opportunities the UN has given her over the years but feels it is time to seek a "different" kind of humanitarian work.

In a statement, she said: "I am grateful for the privilege and opportunity I have had to work with so many outstanding and dedicated UNHCR field officers and other colleagues doing lifesaving work globally, and to serve as Special Envoy. I will continue to do everything in my power in the years to come to support refugees and other displaced people. After 20 years working within the UN system I feel it is time for me to work differently, engaging directly with refugees and local organisations, and supporting their advocacy for solutions."