Image copyright Reuters Image caption Patty Duke began her career as a child star

US actress Patty Duke, who won an Oscar for playing Helen Keller in The Miracle Worker in 1963, has died aged 69.

As well as a best supporting actress Oscar, Duke won an Emmy in 1980 for playing Helen Keller's teacher in a TV movie version.

Duke also starred in The Patty Duke Show in the 1960s in which she took the roles of "identical" teenage cousins.

She was the mother of actor Sean Astin, who played the hobbit Sam in the Lord of the Rings trilogy of films.

Her representative, Mitchell Stubbs, said she died early on Tuesday of sepsis from a ruptured intestine.

She underwent a heart bypass in 2004.

Mr Stubbs said: "She was a wife, a mother, a grandmother, a friend, a mental health advocate and a cultural icon. She will be missed."

Image copyright Reuters Image caption Patty Duke's sons, Mackenzie Astin, left, and Sean Astin, are both actors

A statement from her family read: "This morning, our beloved wife, mother, matriarch and the exquisite artist and champion of mental health, Anna Patty Duke, closed her eyes, quieted her pain and ascended to a beautiful place."

She died in Coeur D'Alene, Idaho, according to Astin's publicist.

The actor thanked all those who expressed their condolences over his mother's death.

"We're so grateful to her for living a life that generates that amount of compassion and feeling in others,'' he told the Associated Press.

He said she had "really suffered" with her illness, adding the last few days had been "a really, really, really hard process. It was hard for her, it was hard for the people who love her to help her".

'Wonderful and talented'

Duke was a child star, making her first TV appearance at the age of 12.

In The Miracle Worker, 16-year-old Duke played blind and deaf girl Helen Keller whose tutor - played by Anne Bancroft - breaks through her isolation and helps her to communicate.

Among those who have paid tribute was Little House on the Prairie star Melissa Gilbert, who appeared as Keller in the TV remake of the film opposite Duke, who played teacher Annie Sullivan.

"I know she's in a better place. I will miss her every day but I will find comfort in the words of Helen Keller: 'The best and most beautiful things in the world cannot be seen or even touched - they must be felt with the heart'," Gilbert said.

Image copyright AP Image caption Patty Duke won a best supporting actress Oscar in 1963 for The Miracle Worker when she was 16

US TV host Larry King said: "I admired Patty Duke for her bravery and work on mental health issues. And, what an actress!''

Actor Chris Colfer, who starred opposite Duke on a 2013 episode of Glee also paid tribute: "So sad to hear of Patty Duke's passing. She was a wonderful and talented person. I loved getting to work with her.''

Among Duke's other awards included Emmys for My Sweet Charlie in 1970 and Captains and the Kings in 1976.

She also appeared in the Broadway musical Oklahoma!.

In her autobiography, Duke revealed that in the 1980s she had been diagnosed with bipolar disorder.

In later life she became a strong advocate for increasing awareness, funding and research for people with mental illness.