Bieber's acting barmy! Justin covers his face with sequined skull scarf as he leaves the BBC and hides under a taxi seat

What have you got to hide? Justin Bieber covered his face with sequined skull headscarf as he left the BBC Radio studios in London today

Justin Bieber is experiencing some growing pains as he makes the transition from teen idol to full-grown superstar. 

The 18-year-old has been exhibiting some rather peculiar behaviour lately, from hiding under a seat in his taxi to wearing a scarf over his face while exiting London's BBC studios.

Unusual statement: Justin's accessory wasn't one he's been seen wearing before

He grinned, and appeared in good spirits, but the unusual accessory was undoubtedly a step away from his normal look.

Justin wore a slightly sparkly black leather jacket, with a grey hoodie underneath, and black jeans teamed with black trainers.

He didn't remove the scarf to pose up with a besotted fan, and it remained affixed to his face for the whole journey.

Justin also provoked comment yesterday, when he hid first behind his iPad and then under a seat as he took a taxi with his little sister Jazmyn.On Monday the 18-year-old was his usual squeaky clean self as he enjoyed 

a cuddle with two teenagers in Madrid, Spain.

Slipped off: The scarf fell down just before Justin made his way outside

As they nuzzled into their idol, sheer joy could be seen on their faces as they fought back the tears and gazed adoringly at him.

The Boyfriend singer looked pleased with himself as she stretched his arms around both females and even gazed back at them.

The Canadian star was dressed in a plain white T-shirt, light jeans and black trainers for his interview on the El Hormiguero show where he sang and fooled around.

Wasn't put off: One ardent fan was especially keen to get close to the star

Kept it on: Justin didn't take his scarf off to smile for the camera

The teenager was also kind enough to satisfy his fans who hadn't been lucky enough to be inside the studio, but were instead waiting patiently for him outside.

Bieber showed his gratitude by serenading them from a large window of the building, beaming as he did so.

However some of his other recent behaviour hasn't elicited such a positive response.

Don't look at me! Justin also hid his face behind an iPad in a taxi yesterday

What's he doing? Justin's little sister Jazmyn didn't seem too perturbed

Justin was accused of roughing up a photographer last month outside a shopping centre.

And if the pop star was hoping the situation would go away quietly, he was sorely mistaken, as it has been reported his case will be referred to the Los Angeles County District Attorney for possible criminal prosecution.

If he is charged and convicted, he could face up to six months in prison.

Retreated further: Justin then appeared to hide under the seat

According to TMZ, police have decided to refer the case to prosecutors.

However the website claims that the move is typical procedure when dealing with high-profile cases such as this.

The 18-year-old is wanted for questioning by Los Angeles County Sheriff's investigators.

The scuffle allegedly happened when the photographer tried to snap pictures of Bieber and his girlfriend Selena Gomez, after they walked out of a cinema at The Commons in Calabasas.

The Justin we know: The pop star posed up with two female fans at Vertice Studio in Madrid on Monday