I have an official passport (diplomatic).do I need to have Visa to go to mainland China via Hong Kong?

I have been selected to go to PRC Via Hong Kong for an official Training for a period of 1 week. I have an official Passport too,when I proceeded to the Chinese Embassy in Colombo, Officer there informed me that it is no need to have one as I'm having an Official Passport. please let me know the truth as early as possible.

your faithfully
Rodrigo