In the wake of his surprise loss not just to Donald Trump but to Marco Rubio in the South Carolina primary, Ted Cruz' campaign suffered another embarrassment after a video purporting to show him mocking the Bible was exposed as a fake.

Posted by the DPolitics website, the 21-second video shows Rubio walking into a hotel lobby past Rafael Cruz – Ted Cruz' father – and a member of Cruz' team reading a Bible. Rubio says: "Got a good book there" but adds "Not many answers in it."

The conservative website The Right Scoop accused Rubio of mocking the Bible, saying: "Was he saying that because Rafael Cruz is Evangelical and he's Catholic? That seems like small justification to be so snide about the Bible. Good luck with Evangelicals after that, Marco."

However, the video was incorrectly subtitled and Rubio actually said, "All the answers are in there."

Cruz' communications director Rick Tyler was forced to issue an apology. He said: "The story showed a video of the Senator walking past a Ted Cruz staffer seated in the lobby of a hotel reading his Bible. The story misquoted a remark the Senator made to the staffer. I assumed wrongly that the story was correct. According to the Cruz staffer, the Senator made a friendly and appropriate remark. Since the audio was unclear, I should not have assumed the story was correct."

Rubio's communications director Alex Conant accused the Cruz campaign of a "dirty trick".