Green Party MP Jan Logie and an Australian Greens senator are travelling to Sri Lanka this week, in what they call a fact finding mission in the lead-up to the Commonwealth Heads of Government meeting.
Prime Minister John Key will attend the meeting in Colombo, amid calls for him to send a strong message to Sri Lanka about its alleged human rights abuses.
Human rights advocates want an independent investigation into allegations Sri Lankan government forces committed war crimes towards the end of a 26-year civil war that ended in 2009.
The United Nations says 40,000 civilians were killed in the last five months of the conflict.
Canada's Prime Minister is boycotting this year's summit but New Zealand says it's more productive to attend and engage with Sri Lanka.
Ms Logie says she believes she and her Australian colleague will be safe given they are parliamentarians.
Tamil and a human rights activist M. Malathy, who became a New Zealand citizen, was detained in a government-run camp when she returned to Sri Lanka in 2009.
She bribed her way out of the camp where she said conditions were terrible and unhealthy and the community was in a bad psychological state.
Ms Malathy is calling for other countries to block Sri Lanka from the Commonwealth chairmanship, and condemn its human rights record.