The United Nations and Amnesty International are among many bodies that have issued reports with strong concerns about how the war ended, with the deaths of thousands of civilians.
The concerns internationally extend to a lack of purpose to examine possible war crimes that took place as well as on on-going crackdown on dissent.
Canada's Prime Minister, Stephen Harper, will not be attending because of the human rights situation and India is thought to be considering its participation.
Mr Mc Cully said he wanted to encourage progress to take place in Sri Lanka before the Chogm meeting and to be clear that such progress would be "the framing through which many countries attending would be seeing their participation this year."
He said one of the big concerns was been lack of progress on devolution, and particularly devolution in the north, where the Tamil Tigers seeking self-rule were defeated.
"Their response on that was encouraging.
"I received very strong assurances that elections will held in September in the north and the planning is being undertaken for that purpose and that that would provide a basis for some of those devolution recommendations."
Mr McCully said there were two ways of looking at Sri Lanka's hosting of the Commonwealth meeting.
"One is to simply point to the issues around reconciliation and say the hosting decision was one the Commonwealth shouldn't have made. Well the fact is they have made that decision and the meeting is going to take place.
"The second way to view is to say 'Look, this really does create an environment in which there is going to be quite strong international scrutiny of progress being made on the reconciliation front and it is important that they understand that that is the way we see the meeting and that we, therefore encourage further progress between now and November in that way."
He would be discussing his meetings with other foreign ministers, including Australia's, Bob Carr.
