In Hong Kong, there is no statutory right that entitles an employer to instruct their employees to take unpaid leave. Therefore, unless there is an express provision in the employment contract, the employer cannot unilaterally force an employee to take unpaid leave.
If an employer decides to force an employee to take unpaid leave against his/her wishes, in the absence of an express contractual term, it could amount to a breach of contract. Where an employee volunteers to go on unpaid leave, it is suggested that the agreement is documented in writing.