Kenya's feuding parties have agreed to rewrite the constitution within a year in an effort to end post-election violence, but have yet to strike a deal on power-sharing, a government negotiator said on Thursday.

Talks were earlier adjourned until Monday, dashing chief mediator Kofi Annan's hopes of a final political settlement this week to resolve a crisis sparked by President Mwai Kibaki's disputed re-election.

More than 1,000 people have died and 300,000 have been driven from their homes in turmoil that has shattered Kenya's image as one of Africa's most stable democracies.

"Both parties reached agreement on a wide-ranging sphere of issues affecting the country ... among them being to write a new constitution within a year," government negotiator Mutula Kilonzo told Reuters.

But the two sides have yet to strike a deal on the most contentious issue -- the structure of the government.

Kilonzo said the parties agreed on "serious constitutional, legal and institutional reforms" in a four-page document, but gave no further details.

Opposition officials declined to comment on the record. Annan's spokesman also declined to comment.

The former U.N. chief is due to brief the press on Friday.

Opposition leader Raila Odinga accuses Kibaki's team of rigging the December 27 vote while Kibaki says he won fairly.

Kenyans have been calling for a new constitution since the early 1990s to replace one dating back to the eve of independence from Britain in 1963, which critics say fosters graft and tribalism because of the president's immense powers.

The last attempt to pass a new constitution failed in 2005 when Kenyans rejected a government-backed draft in a referendum.

OPTIMISM VS REALITY

In a bid to shore up Annan's mission, U.S. President George W. Bush has asked Secretary of State Condoleezza Rice to head to Kenya to tell its leaders there must be a return to democracy.

"There must be an immediate halt to violence, there must be justice for the victims of abuse and there must be a full return to democracy," Bush said.

Party sources say both sides have agreed in principle to some form of power-sharing and are focusing on the details in private. After returning from the talks at a luxury safari lodge, the government's top negotiator played down expectations.

"Optimism is not the same as reality, but we are making progress," Justice Minister Martha Karua told reporters.

"We are making progress, we have not reached agreement."

The two parties are expected to set up a South African-style truth, justice and reconciliation commission to investigate abuses including ethnic attacks and killings of protesters by police.

On Thursday, the government-funded Kenya National Commission on Human Rights (KNCHR) said ringleaders should not be forgiven.

"The worst perpetrators and planners of the types of violations that have taken place over the recent weeks must never be exempted," KNCHR commissioner Hassan Omar Hassan told a news conference. "To do so would be a travesty of justice."

The group's call added to international pressure for the perpetrators of violence to be held accountable.

Various Western nations have threatened travel bans or the freezing of assets of guilty parties and have also said anyone derailing the Annan talks would face "consequences".

The trouble has exposed deep rifts over land, power and wealth that date from the British colonial era and have been stoked by some Kenyan politicians ever since.

On Thursday, the government said it was setting up a resettlement department to help displaced people return to their homes. To encourage them, it said it was also building 32 police stations in areas afflicted by the violence.