How Should I Handle a Probation Extension for Underperforming Staff? Seeking Advice

I am a branch manager of a private bank. A new staff member is working as my subordinate during a probation period of six months. Some targets were given to him, but he could not achieve them. Now, the HR department is asking me to send a memo recommending an extension of his probation period by three months. I should also mention in the memo that his probation period should be extended due to unsatisfactory performance in various areas. Kindly help me with the letter.

Sample Letter to HR Regarding Probation Extension

During the probation period, between [start date] and [end date], [Name] was assigned the following tasks by the undersigned to complete within the specified time stated below. The necessary guidance was also provided from time to time by his/her mentor(s) for the tasks mentioned herein, with the intent that the individual would acquire the requisite working knowledge and skills required to complete the assigned work. Regular reviews of the work progress were conducted jointly with the individual and mentor, and feedback was provided for improvement in performance both verbally and in writing, as per the enclosure.

It is, however, observed that the individual has not gained a satisfactory level of skills and knowledge to perform the work, despite the guidance and feedback provided. Therefore, it is felt that his/her performance should be monitored for a further three months before assessing the completion of the probation period. It is recommended that the probation period of [Name] be extended by a further three months, effective from [start date] until [end date].

Regards,
[Your Name]