The 1984 killing of thousands of ethnic Somalis in Kenya is to be investigated, Prime Minister Raila Odinga says.
Mr Odinga said the attorney general should ensure those responsible for the killings are brought to justice.
Witnesses say some 5,000 men were taken to an airstrip and denied food and water for five days before being shot by the army, which had been sent to the area to stop clan violence.
The government has previously said it could only confirm 365 deaths.
"We are yet to fully understand what exactly happened at Wagalla airstrip where thousands of people were killed," Mr Odinga said in the town of Wajir at a ceremony to mark the 27th anniversary of the killings.
"We are yet to know who gave the orders to the soldiers and who made the decision."
He also ordered a museum to be built to honour those who were killed in the area which is primarily inhabited by ethnic Somalis.
It was the worst human rights violation in Kenya's history, according to Truth, Justice and Reconciliation Commission head Ron Slye.
The commission was established following a 2008 peace agreement to end post-election violence to look into present and past atrocities committed in the country.
Last year, a new constitution was implemented, intended to end years of human rights abuses.