How to get list of permission groups from Site Permissions using .net Client Object Model

Hi,

I want to get the list of permission groups which are under "site permissions" using.Net Client Object Model.

Note: I don't want to get all the permission groups winch are under "people and group".

I have already tried with the below code snipets,

oweb.AssociatedOwnerGroup;

oweb.SiteGroups;

It is always giving the all the groups from "people and group" but not from "Site Permissions".

I have only two grups under "Site Permissions" and around 15 groups under "People and Group", but i am getting full list of groups from "People and Group"

Regards,

Krishna