6.—An employer shall, subject to the right of an employee to give counter-notice under section 10 of the Act of 1967 or to give notice of intention to claim redundancy payment in respect of lay-off or short-time under section 12 of that Act, be entitled to not less than one week’s notice from an employee who has been in his continuous employment for thirteen weeks or more of that employee’s intention to terminate his contract of employment.