Buffy the Vampire Slayer star James Marsters has been left "heartbroken" by claims the hit show's creator treated his castmates terribly.

The actor, who played vampire Spike on the iconic 1990s TV series, has become the latest cast member to speak out after Charisma Carpenter and Michelle Trachtenberg denounced Joss Whedon's behaviour in damning social media posts last week.

Their allegations came several months after Justice League star Ray Fisher accused Whedon of being unprofessional on the set of the DC blockbuster he took over when director Zack Snyder was forced to step down due to a family tragedy.

In Twitter and Instagram posts shared on Friday, Marsters wrote: "While I will always be honored to have played the character of Spike, the Buffy set was not without challenges."

He went on: "I do not support abuse of any kind, and I'm heartbroken to learn of the experiences of some of the cast. I send my love and support to all involved."

Marsters' statement came as fans started calling on fellow Buffy stars David Boreanaz and Alyson Hannigan to speak out.

The show's star, Sarah Michelle Gellar, has spoken out to support Carpenter and Trachtenberg but refused to weigh in on their allegations, while castmate Eliza Dushku has also offered her support to the actresses.

Co-star Anthony Head told TV show This Morning last week he was disappointed that he was not made aware of his castmates' issues on set.

"This is not a man saying he didn't see it so it didn't happen," he said, adding: "I am gutted - I am seriously gutted... I was like a father figure. I would have hoped someone had come to me to talk about it."

Whedon has yet to make a public comment about the allegations.