Big Sean has issued a warning to Justin Bieber after the singer was seen hugging Ariana Grande on-stage - Big Sean's girlfriend.

Ariana Grande and Justin Bieber on stage

Ariana Grande and Justin Bieber on stage

Unhappy with the embrace they shared during and after their performance of track 'Love Me Harder' during Grande's concert at the Forum in Inglewood, Los Angeles on Wednesday night, he let his feelings be known.

During the duet, Ariana even broke into fits of giggles as Justin draped his arms over her shoulders and Big Sean took to Twitter to express his anger.

In one deleted tweet, he simply wrote: "Wow."

While in another, now erased, post he warned: "This kid is about to learn not to touch my girl like that. Beliebe it. (sic)"

Justin and Ariana also sang 'As Long As You Love Me' together at the concert, part of her 'The Honeymoon Tour'.

Ariana, 21, and Big Sean, 27, have been dating for over a year and are said to be in a "serious" relationship, but that didn't deter fans from taking to social media to declare Justin, 21, and Ariana looked "cute together" and should "get together".

Another fan posted online: "I just can't get over Ariana Grande and Justin Bieber. I mean yes Ariana and Justin have a really good chemistry on stage but what we all have to respect Sean and Ari's relationship."