Charles Manson has obtained a marriage licence to tie the knot with a 26-year-old woman who visits him in prison.

It was not immediately clear if the 80-year-old mass murderer had set an exact date to marry Afton Elaine Burton, who runs a number of websites claiming he is innocent.

A copy of the marriage licence, issued on 7 November, was seen by the AP news agency on Monday.

Ms Burton moved to Corcoran, California, nine years ago to be near Manson who is being held at Corcoran State Prison.

In an interview last year with Rolling Stone magazine, Ms Burton said she planned to marry Manson.

However, the infamous criminal denied at the time that a wedding was in the works.

Ms Burton, who goes by the name Star, told AP on Monday that she loves Manson and they will marry next month.

"Y'all can know that it's true," she said. "It's going to happen." She added: "I love him."

The marriage licence expires in 90 days.

California Department of Corrections spokeswoman Terry Thornton confirmed the licence had been filed with the prison.

Manson has been in jail for 45 years for the infamous Tate-LaBianca murders.

He and his followers were convicted in the gruesome killings of pregnant actress Sharon Tate, the wife of film director Roman Polanski, and four others at her estate on 9 August 1969 as well as Leno and Rosemary LaBianca the following night.

Manson has stopped attending parole hearings, saying prison is his home and that he wants to remain there.

He is next eligible for parole in 2027.

Two of his 'Manson family' followers - Leslie Van Houten and Patricia Krenwinkel - also remain in prison, while a fourth, Susan Atkins, died of cancer behind bars.