Solange Knowles attacked Jay Z in lift 'because he planned to go to Rihanna's party without Beyonce'

Solange Knowle's attack on Jay Z in a hotel lift was allegedly sparked by his plans to go to Rihanna's Met Ball after party without Beyonce.

The incident in a lift at the Standard Hotel in New York was reportedly ignited after Solange learned of Jay's plan to attend the party alone.

A source told the New York Daily News that the singer asked Jay why he couldn't just go home with Beyonce - and asked her "why does your husband need to go to the club right now?"

The source claimed Jay replied to Solange: "you are one to talk."

The claims come after incredible footage showing Jay Z being attacked in a lift by Solange was posted online.

The rapper and his wife stepped into an elevator with her singer sibling before she snapped and started to kick out, unleashing a violent attack which was captured by surveillance cameras.

The video obtained by gossip website TMZ, shows a man - seemingly a bodyguard - stepping in and holding Solange back after she assaulted her sister's husband.

The man who stepped in to stop the assault is seen hitting the emergency stop switch in the lift - which stopped the fight spilling out.

The outburst has come as a shock, particularly when the trio looked to be getting on fine when the sisters joined forces as Coachella last month.

-The Mirror