Ashton Kutcher has resigned from an anti-child sex abuse organisation he co-founded amid backlash for his support of That ‘70s Show costar Danny Masterson.

Following news Kutcher and his wife, Mila Kunis wrote letters in support of Masterson – who was sentenced to 30 years to life in prison on two accounts of rape this week – the actor has received huge public backlash.

Now, he has announced his resignation from his role as chairman of the board at Thorn, E! News reports.

The 45-year-old No Strings Attached actor released a statement to Time magazine today sharing the reasoning behind his decision: “After my wife and I spent several days of listening, personal reflection, learning, and conversations with survivors and the employees and leadership at Thorn, I have determined the responsible thing for me to do is resign as Chairman of the Board, effectively immediately,”

He added, “I cannot allow my error in judgment to distract from our efforts and the children we serve.”

In the statement which was issued in full to the US news outlet, Kutcher continued to say by writing a letter in support of his longtime friend, he has undermined the organisation’s efforts.

“As you know, I have worked for 15 years to fight for people who are sexually exploited,” the actor stated. “Victims of sexual abuse have been historically silenced and the character statement I submitted is yet another painful instance of questioning victims who are brave enough to share their experiences. This is precisely what we have all worked to reverse over the last decade.”

He signed off the resignation offering a “heartfelt apology to all victims of sexual violence and everyone at Thorn who I hurt by what I did.”

The father of two also said he remains “proud” of the work Thorn has accomplished during his time with them over the past 10 years.

Thorn was founded by Kutcher and his ex-wife Demi Moore in 2012 after the former couple watched a documentary highlighting the issue of child sex trafficking in Cambodia.

Affiliations with the organisation have seen the actor testify at a 2017 hearing with the Senate Foreign Relations Committee in which they examined America’s progress in ending human trafficking and modern slavery.

Kutcher’s decision comes after he and Kunis’ character letters to LA Superior Court Charlaine Olmedo in support of Masterson went public, with Kutcher describing his former friend as “nothing but a positive influence” and “an extraordinary honest and intentional human being”.

He went on to say that he didn’t think Masterson was an “ongoing harm to society”.

Kunis then dubbed the now-charged actor as an “amazing friend, confidant, and above all, an outstanding older brother figure” to her.

The A-list couple have since shared a video statement firmly stating that they “support victims” and did not write the letters to “question the legitimacy of the judicial system or the validity of the jury’s ruling.”