Justin Bieber has revealed he has been struck by a rare virus that caused half of his face to be temporarily paralysed.

The Canadian singer was recently forced to cancel dates in North America.

In a video on Instagram, Bieber, 28, revealed he has been diagnosed with a rare syndrome called Ramsay Hunt, which left the right side of his face unable to move.

“Obviously, as you can probably see from my face, I have this syndrome called Ramsay Hunt and it is from this virus that attacks the nerve in my ear and my facial nerves, and has caused my face to have paralysis,” he told fans.

“As you can see this eye is not blinking, I can’t smile on this side of my face,” he added.

“It’s pretty serious, as you can see, I wish this wasn’t the case.”

He added: “Obviously, my body’s telling me I gotta slow down.”

Bieber said he was certain he would get better, and would use time to “rest and relax”.

The NHS says Ramsay Hunt syndrome is caused by a virus in the facial nerve and is a more severe cause of facial paralysis.

Possible symptoms include blisters in the ears and on the roof of the mouth, as well as facial weakness.

The syndrome can be treated with steroids, antiviral medication and facial rehabilitation.

The NHS says less than half of patients recover completely.