Celtic FC have been urged to scrap their use of zero-hours contracts.

Members of Unite's Scottish youth committee said they have become aware some employees in the club's retail stores are working on the casual arrangements.

The committee has now written to Celtic chief executive Peter Lawwell asking for a meeting to discuss the club's use of the contracts.

Celtic have questioned the motivation behind the letter, however, which they said was released to the media at the same time as it was given to the club.

The controversial zero-hours contracts cover a range of arrangements that mean workers have no guaranteed weekly hours or income and are only paid for the hours they work.

Unite became aware of the issue after one of its members who worked at a Celtic store came forward and revealed some of the employment practices she experiences.

STV News understands she was offered last-minute shifts over the festive period to then be told she did not have to come in.

The union claims Celtic are currently advertising vacancies for zero-hours roles.

Unite's letter says: "The Unite youth committee is acutely aware of the proud history that Celtic FC has and its historical traditions.

"From its inception as a football club 'formed for the maintenance of dinner tables for the children and the unemployed', to its outstanding community outreach and social mobility programmes, Celtic FC has the proud reputation of being more than just a club.

"However, the use of exploitative zero-hours contracts contradicts the proud tradition of Celtic FC of being a vehicle of social mobility and social justice.

"Being trapped within a zero-hours lifestyle by not knowing when you will next get another wage, by not knowing if you have enough money to survive until the next shift is in complete opposition to the values ingrained within the traditions of Celtic FC."

A spokesman for the club said: "The first communication of any kind that we received from this organisation was a letter which was released simultaneously to the media.

"We have to question the motivation behind it and why Celtic, of all the companies in Scotland, was targeted in this way.

"We have excellent relationships with our workforce and we will continue to discuss employment related issues with them in an open and constructive manner and not through the media."