Actor Alec Baldwin says he did not pull the trigger on the prop gun which fired and killed a cinematographer on the set of the film, Rust.

In an interview with the US ABC's George Stephanopoulos, which will be released on Thursday, Mr Baldwin denied being the one to pull the trigger.

ABC released a clip on Wednesday showing Mr Baldwin breaking down in tears while describing Halyna Hutchins, the cinematographer who was killed on the set.

Director Joel Souza was also injured.

"I didn't pull the trigger," Mr Baldwin said.

It was Mr Baldwin's first sit-down interview since the October 21 shooting on the set of the western film, Rust.

Authorities have said Mr Baldwin was told the gun was safe to handle, but they continue to investigate how a live round ended up in the weapon.

Mr Baldwin was asked during his interview with Stephanopoulos how a live round ended up on the set.

"I have no idea," the actor said.

"Someone put a live bullet in a gun — a bullet that wasn't even supposed to be on the property."

Investigators have described "some complacency" in how weapons were handled on the set.

They have said it is too soon to determine whether charges will be filed, amid independent civil lawsuits concerning liability in the fatal shooting.

AP/ABC