Ashton Kutcher and Mila Kunis apologise for Danny Masterson character letters

Ashton Kutcher and Mila Kunis have apologised for submitting letters vouching for Danny Masterson's good character ahead of his sentencing for rape.

The Hollywood couple's That '70s Show co-star was sentenced to 30 years to life in prison on Thursday after he was convicted on charges of raping two women relating to incidents in the early 2000s.

Kutcher and Kunis drew heavy criticism after it emerged they were among more than 50 people who wrote to the judge to support the disgraced star ahead of his sentencing.

In his letter, the Punk'd star called his old castmate an excellent "role model", while the Ted actress called him an "amazing friend, confidante, and, above all, an outstanding older brother figure".

In a video posted on their Instagram page on Saturday, the pair apologised for the letters, with Kutcher saying: "We are aware of the pain that has been caused by the character letters that we wrote on behalf of Danny Masterson."

Kunis, 40, added: "We support victims. We have done this historically through our work and will continue to do so in the future."

Her 45-year-old spouse went on to explain that Masterson's family reached out to them to write character letters to "represent the person that we knew for 25 years".

She continued: "The letters were not written to question the legitimacy of the judicial system or the validity of the jury's ruling."

Kutcher went on to say that the letters were only intended for the judge, with his wife concluding, "Our heart goes out to every single person who's ever been a victim of sexual assault, sexual abuse or rape."

Other stars from That '70s Show who wrote similar letters include Debra Jo Rupp, who played Kitty on the acclaimed sitcom, and Kurtwood Smith, who played her husband Red.

Kutcher and Kunis' letters and subsequent apology have both provoked anger, including thinly veiled criticism from fellow star Christina Ricci. According to the journalist Yashar Ali, one of Masterson's victims also called their social media apology "incredibly insulting and hurtful".