Tulisa Contostavlos "desperately trying to diffuse the situation but the argument was getting heated," a source said.

Tulisa Contostavlos was involved in an airport bust up in which her personal assistant was allegedly headbutted.

The 'Young' hitmaker was en route back to London with her PA and best friend Gareth Varey after her performance at In: Demand Live at Glasgow's SECC on Sunday when the pair were caught up in a fracas with a fellow passenger.

Gareth allegedly heard a man making a derogatory comment about Tulisa in a shop in Glasgow airport and after confronting him about it, a row broke out before Gareth was attacked.

The group then went to their departure gate, where a witness said they were agitated about the incident.

The onlooker told the Daily Record newspaper: ''There was a lot of talk about one of Tulisa's group being headbutted. They all wanted to sort it out before take-off.

''Tulisa stayed back with a girl and a guy, where they continued arguing their case with staff.

''She was desperately trying to diffuse the situation but the argument was getting heated.

''Tulisa didn't want to leave the matter unresolved as, she said, they would be 30,000ft in their air. They didn't want anything else to kick off.''

Police escorted Gareth off the flight and questioned him and the other suspect before Tulisa and Gareth flew to London together.

Gareth posted a tweet which read: ''Let's take a moment to think about the p***k that felt the need to headbutt me,'' although he later deleted it.

Police said: ''We were called to an incident in Glasgow airport involving two people. They were spoken to. No complaint was made.''

A spokesman for Tulisa added: ''There was an argument at the airport but no further action is being taken.''

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