There’s no letting up in the bitter feud between hot-head actors Shia LaBeouf and Alec Baldwin!

The furious Transformers star is holding a grudge against the 30 Rock actor -- blaming him for his firing from the Broadway play Orphans — and vowing to get even, a source tells Breaking Celebrity News exclusively.

In addition, LaBeouf, 26, is so bitter towards Baldwin, the source says, that he doesn’t want to work with him ever again!

“Shia just can’t let this one go, he’s disgusted with Alec for getting him axed from Orphans,” the source says.

“He would never dream of whining to a director about a co-stars’ performance, which he genuinely believes Alec did.

“Shia thinks Alec told director Daniel Sullivan that he wasn’t up to scratch for the role and they should seek a replacement before the play’s premiere.

“He says that Alec always undermined him for his lack of theater experience, but Shia HAS done theater before and isn’t just a movie star, as Alec claimed.

“Now, Shia is adamant that he doesn’t want to work with Alec again, and he has vowed to get even with him. He thinks he acted unprofessionally, that he's a bully and out-of-touch with reality,” the source says.

As Breaking Celebrity News previously reported, LaBeouf ensured he was sitting front row and center for the preview of Orphans last week – only a month after his bust-up with Baldwin.

But, Shia wasn’t there for peer support - far from it – instead, he hoped his presence would unnerve Baldwin.