High-scale department store Myer is suing fashion designer Kym Ellery for apparently reneging on their exclusivity contract. The row started when the Sydney-based designer negotiated with Myer's main rival, David Jones.

Myer claims that Ellery agreed that the department store would carry her designs exclusively. However, it had learned that she had also sign an agreement with David Jones. It is now suing Ellery for breach of contract over their failure to deliver the ordered clothes for autumn-winter 2013 collection.

Barrister Peter Murdoch QC for Myer told the Victorian Supreme Court on Monday that Ellery signed a three-year exclusive contract with Myer in August 2011. The contract stipulated that she was to supply Myer clothing from her collection, and that she wasn't allowed to supply to any other retailers in Australia with 15 or more stores.

Her contract also required her to be a judge in the department store's sponsored Fashion on the Fields event. However, she was fired from the position when Myer found out that she had also signed with David Jones. Her clothes were to be worn by celebrities Lara Bingle and Rebecca Ludd at the event.

"The reason for the exclusivity agreement is because the time and energy and expense is something that reveals a benefit after a period of time," Murdoch told the court, as quoted by the Herald Sun.

Court documents reveal that Ellery met with a staff from David Jones in August, a month before Myer placed an order for the autumn 2013 collection, which Ellery failed to fulfil. David Jones sent her an exclusivity letter on November 7, but she only signed it after two days. The petitioner did not know about the contract until December 2.

Myer wants an injunction to prevent the designer from supplying any more clothing from her labels Ellery Land and L'America to David Jones.

The hearing is expected to continue until Thursday.