Tamil women held photos of missing relatives at a protest outside the summit
Sri Lanka is set to start a survey to determine the number of people killed during the country's 26-year civil war, the government says.
The census will collect information on deaths, missing people and damage to property from 1983 to 2009, it said.
It comes amid international pressure over allegations of mass civilian deaths at the end of the conflict.
A Commonwealth summit held in Sri Lanka this month was overshadowed by claims of war crimes.
Sri Lanka's army defeated separatist Tamil Tiger rebels in May 2009.
Allegations of atrocities during the closing stages of that war have dogged the government ever since. The rebels were also accused of abuses.
The government has strenuously denied such allegations and insist it is on the path of reconciliation
Officials "will conduct an island-wide census to assess the human and property damages occurred during nearly three-decade long conflict," a government statement said on Wednesday.
"This census, which has to be completed within six months will be launched on Thursday 28 November."
Some 16,000 officials will be visiting the homes of families affected to collect information, according to the state-run Daily News.
The announcement comes after Sri Lanka hosted a Commonwealth summit dominated by protests over treatment of the Tamils. The leaders of India, Mauritius and Canada boycotted the event.
The spotlight has fallen on the final phase of that war when civilians were hemmed into a thin strip of land on the north-eastern coast - both sides are accused of atrocities here.
The UN says as many as 40,000 Tamil civilians may have been killed.
Sri Lanka's President Mahinda Rajapaksa rejected calls at November's summit for an independent inquiry into alleged war crimes, and said the country needed more time to heal the wounds of civil war.
State media say the government's latest move to count the country's war dead comes as part of its internal report, the Lessons Learnt and Reconciliation Commission (LLRC), published in November 2011.
Human rights groups say that the LLRC is deeply flawed and has provided no accountability for atrocities the government is alleged to have committed during the war. The government insists the commission will provide justice.