Selena Gomez says she will always come to the defence of ex-boyfriend Justin Bieber.

The couple went public in 2011 and dated on and off for nearly two years before splitting a few months ago.

Rumours about the status of their relationship have floated around ever since as the former couple have been seen out together on more than one occasion.

Selena addressed the speculation during an appearance on US breakfast programme Good Morning America on Friday.

She said they're simply able to remain close friends because they "have had such a history together".

"I'll always care about him and protect him if anybody tries to be mean," she said.

Justin hasn't received much favourable press in recent months.

The 19-year-old was recently depicted urinating into a club restaurant's mop bucket and has been accused of spitting in a man's face on a night out. Los Angeles police also launched an investigation into Justin's alleged reckless driving following several complaints from his neighbours.

Selena abruptly ended an interview earlier this month after she was pressed about her ex's behaviour.

"You're, you know, probably as close a friend to Justin Bieber as they come. Is there something about him that we don't get or we don't understand?" showbiz reporter Dean Richards asked Selena in a video interview.

"I mean, there is one story after another of, you know, pretty outrageous behaviour that we're reading about."

Selena looked around in confusion as the reporter persisted.

"What don't we get about him or what is it that he's not getting out there?" Dean asked.

The journalist never received an answer. Instead, Selena offered an awkward smile before the screen went black.