Toshiba has told its JV partner Western Digital to stop interfering with the sale of the Japanese company's chip unit, disputing claims by the U.S. firm that it had breached a joint venture contract.

Western Digital, which is a partner in Toshiba's main semiconductor plant as well as one of the bidders for the chip business, has argued that the Japanese firm is violating their contract by transferring their joint venture's rights to the newly formed unit.

In a May 3 letter sent by Toshiba's lawyers, the Japanese conglomerate disputed Western Digital's argument and said it would pursue all available remedies if it saw continued interference in the sale process.

Western Digital's "campaign constitutes intentional interference with Toshiba's prospective economic advantage and current contracts. It is improper, and it must stop," the letter.

In a separate letter, also dated May 3, the general manager of Toshiba's legal affairs accused Western Digital of failing to sign some joint venture agreements.

If Western Digital refuses to sign by May 15, the chip unit would protect its intellectual property rights by suspending Western Digital employees' access to all of the unit's facilities, networks and databases, the letter said.

Western Digital declined to make any comment.