He may be one of the biggest pop stars on the planet, but Justin Bieber is not immune to illness.

The 28-year-old took to social media over the weekend to share the reason he has been forced to cancel concerts on his Justice tour in New York., Washington DC and Toronto.

He said that he had been diagnosed with Ramsay Hunt Syndrome, after a virus had damaged nerves in his ear and caused the right-hand side of his face to become paralysed.

In a three-minute video shared on Instagram, he tries to blink and smile to no avail.

"It is from this virus that attacks the nerve in my ear in my facial nerves and has caused my face to have paralysis," he explained. "As you can see, this eye is not blinking. I can’t smile on this side of my face. This nostril will not move, so there’s full paralysis on this side of my face."

He added that he was not sure how long it would take him to recover, but he had been doing facial exercises in a bid to his face back to 'normal'.

“This is pretty serious as you can see," he said. “I wish this wasn’t the case but obviously my body is telling me I gotta slow down. I hope you guys understand, and I’ll be using this time to just rest and relax and get back to 100% so I can do what I was born to do. But in the meantime, this ain’t it.

"We don’t know how much time it is going to be but it’s going to be OK, I have hope and I trust God. I trust it is all for a reason. I’m not sure what that is right now but in the meantime I am going to rest."

Ramsay Hunt Syndrome is a complication of the shingles virus, and can affect those who had chickenpox as children.

Bieber is scheduled to play Dublin on February 28th and March 2nd next year.