NAIROBI, Kenya — The International Criminal Court's chief prosecutor said Thursday that Kenya's postelection violence last year that killed more than 1,000 people was a crime against humanity and pledged to seek an investigation that could result in top officials facing trial.

Luis Moreno Ocampo said he told President Mwai Kibaki and Prime Minister Raila Odinga that he will ask a pretrial chamber in December to allow him to formally open an investigation into the violence that took place between December 2007 and February 2008 after a contentious presidential election.

That would be a relief to Harun Mwangi Macharia, whose 3-year-old daughter died when the church Macharia's family sought shelter in during ethnic violence was torched by Kalenjin warriors. Dozens died in the attack. Macharia's wife saved five of their six children, but she was caught by the flames and suffered third-degree burns.

"So that it is a lesson for future generations, they should be prosecuted without mercy," Macharia said of the violence's perpetrators.

If they are not prosecuted, violence will be "inevitable" during Kenya's next nationwide vote in 2012, Macharia said.

Kibaki and Odinga said Thursday that the government will fully co-operate with the ICC.

"We are ready and willing to work and co-operate with Mr. Ocampo to ensure that those who bear the responsibility for the crimes that were committed are brought to justice," Odinga said.

Violence in Kenya came after rival campaigns disputed the results of the December 2007 presidential election. Several human rights organizations blamed businessmen and politicians in the current administration for orchestrating the violence, which was the worst since Kenya gained independence from Britain in 1963.

The clashes severely damaged Kenya's reputation -- the region's largest economy had long been regarded as a haven of stability in a region roiled by brutal civil wars. Tourism, the country's second largest foreign exchange earner, declined in its wake.

Kibaki and Odinga signed a power sharing deal in February 2008 to end the violence. The deal also detailed wide-ranging reforms seen as essential for Kenya to avoid future violence.

"I consider the conflict in Kenya a crime against humanity," Moreno Ocampo said.

Moreno Ocampo's office has been evaluating whether the Kenyan violence constituted crimes against humanity since January 2008. In July this year, former U.N. chief Kofi Annan, who mediated an end to the violence, sent Moreno Ocampo a sealed envelope with the names of suspected ringleaders named by an independent commission.

The commission kept those names secret, saying they are powerful individuals who could interfere with future investigations, but the commission did say that a handful of Cabinet ministers, businesspeople and police officers are listed.

The commission had recommended that the government form an independent tribunal with Kenyan and foreign judges to try the suspects, arguing that Kenyan courts are not credible. Failing that, it recommended the ICC take over the cases. Both recommendations won wide local and international support.

The government has so far failed to form an independent tribunal, drawing criticism from ordinary Kenyans and diplomats. Kibaki and Odinga said Thursday that the government was still committed to setting up a "local mechanism."

The International Criminal Court would only prosecute the ringleaders of violence. Prosecutions of street-level criminals would have to be carried out by Kenya.

A lawmaker has sponsored a bill aimed at setting up a local tribunal, and parliament will resume debate on the bill next week.

The lawmaker, Gitobu Imanyara, said that Kenyan leaders thought they could avoid dealing with the issue by not creating a tribunal, but that Moreno Ocampo's action on Thursday showed that perpetrators will face trial.

Imanyara said a local tribunal that meets international standards would help Kibaki and Odinga improve their standing in Kenya and abroad, and reduce the need for the international court.