Selena Gomez apparently can't resist Justin Bieber's "charms".

The Spring Breakers star and the 20-year-old bad boy have been on and off since 2010, but they're rumoured to be dating again after Justin posted a video of them dancing to John Legend on Instagram.

Baby singer Justin has experienced trouble with the law recently, including an arrest for DUI in Miami earlier this year and reportedly causing $20,000 of damage to a neighbour's home.

It was also revealed Selena had spent two weeks in rehab in January to deal with personal issues, with some claiming her troubled relationship with Justin was to blame.

Friends and family are said to be less than pleased that Selena, 21, can't resist the singer.

"Selena has fallen for Justin's charms and the two of them have become inseparable again," a source divulged to British magazine Star.

"Even when they're not together they're texting and calling each other, but Selena's friends have been brutally honest with their thoughts and opinions.

"They've told her in no uncertain terms that they think she should keep well away from Justin - they all think he's bad news."

One of those said not be keen on the pair rekindling their flame is 24-year-old Taylor Swift.

The Red singer has been friends with Selena for some time and they've often helped each other through boy troubles.

However, it's been denied that Taylor has "cut off" her friend and an insider added that she sees Selena as a "little sister".