Leonardo Dicaprio and Nina Agdal were reportedly involved in a car crash in the Hamptons.

The actor and his model girlfriend escaped uninjured when the car they were in was rear-ended by a Mini Cooper.

A source told the New York Post's Page Six: ''Leo and Nina got rear-ended, but everyone is doing fine. It was Leo's friend's car.''

An ambulance was called as a precaution and Leonardo checked to make sure everyone was fine.

Meanwhile, after some speculation, Nina's grandmother confirmed the model is dating Leonardo last month, and warned him to ''behave''.

The blonde beauty's gran Lona revealed the pair first met six years ago and admitted they are indeed a couple, but joked the 41-year-old actor would have her to deal with if he upsets her granddaughter.

She said: ''We have not said hello to him [Leonardo] but we hope that he behaves towards her. Otherwise he will get me to deal with.

''I can tell you that it is six years since they first met, and now the relationship apparently developed.''

Nina, 24, has been busy of late and not had much time to see her grandmother, but Lona insists she is ''happy'' with the occasional email.

She added: ''She is rarely home because she is very busy. I have fortunately an email from her once in a while, and I am of course happy.''

The 'Revenant' star and the Victoria's Secret model's friends have insisted their relationship is ''super casual''.