Adding Charts to Google Spreadsheet programatically

[Marco Desira]

I am coding a .NET module which creates spreadsheets in Google Docs/Drive.
I am using a combination of Google Spreadsheets API version 3.0 and Google 
Documents List API version 3.0.
 
I now need to add charts to the spreadsheets. 
I need to create the charts programatically.
 
I cannot find refernence to creating charts in the 2 APIs mentioned above.
 
Can somebody point me in the right direction?
 
Many thanks