Recommendation Letter To Extend Probation Period

I am a branch manager of a private bank. A new staff is working as my subordinate in probation period of six months. Some target had been given to him but could not achieve that. Now the HR department is asking me to send a memo recommending to extend his/her probation period by three months and also I should mention on memo that his probation period should be extend due to
unsatisfactory performance in various areas.
Kindly help me for the letter.

This is feel may be a sample letter to the HR:

" During the period of the probation, between date to date, ... so & so.... .was given the following tasks /assignments by the undersigned to complete within the specified time stated below. The necessary guidance was also given from time to time by his mentor(s) for the tasks as stated herein, with a view that the individual shall acquire the requisite working knowledge and skills required to complete the work assigned to him/her. Regular reviews of the work progress were done jointly with the individual and mentor, feedback was also given for improvement in the performance both verbally and in writing as per enclosure.

It is however observed that the individual has not gained satisfactory level of skills and knowledge to perform the work, inspite of the guidance/feedback provided, and therefore it is felt that his/her performance is to be watched for a further period of three months before assessing the person for completion of Probation period. It is recommended that the Probation period of Shri/ Ms....so & so .. be extended by a further period of three months wef date i.e. tlll ..date."

sanjai