NAIROBI, Kenya (CNN) -- Talks to mediate an end to Kenya's political crisis were to resume Friday morning after being suspended in the wake of a second opposition lawmaker's killing a day earlier, according to a U.N. spokesman.
David Too's killing was the second against a lawmaker in three days; fellow Orange Democratic Movement lawmaker Mugabe Were was gunned down outside his Nairobi-area home on Tuesday.
Odinga has called the killings part of a plan to reduce the number of opposition parliament members. A government spokesman did not respond to a request for comment on the claim.
U.N. Secretary-General Ban Ki-moon was scheduled to arrive in Nairobi on Friday to help bolster the mediation effort spearheaded by his predecessor, Kofi Annan, said U.N. spokesman Nasser Ega-Musa. Ban said he met with Kenyan President Mwai Kibaki on Thursday on the sidelines of the African Union summit in the Ethiopian capital, Addis Ababa.
Ban urged Kenyans to "stop the killings and end the violence now, before it is too late." Watch displaced civilians in a refugee camp outside Nairobi »
"Heed the calls, from Mr. Annan and other world leaders, for restraint, tolerance and peaceful dialogue to resolve contentious issues. Demand it from your leaders," Ban said from the summit.
French Foreign Minister Bernard Kouchner, a co-founder of the group Doctors Without Borders, also denounced the killings and humanitarian toll on Kenya. He announced support for Annan's efforts, while urging the U.N. Security Council to act.
"The two main parties are now facing an historic responsibility: Choose the path of dialogue or bear the burden of a political and humanitarian catastrophe," he said in a written statement.
"Mr. Annan agreed to interrupt the afternoon session, so that members can meet with their constituents and also offer their condolences," Ega-Musa said.
"Both sides joined as one to express their shock and sadness at the untimely death of their parliamentary colleague, Mr. David K. Too."
U.S. Ambassador to Kenya Michael Ranneberger said Washington is "deeply concerned" about Too's killing and offered the FBI's assistance in the investigation. It has also offered assistance in the investigation into Were's killing.
The United States has told the government and opposition it would impose a travel ban on people it identifies as responsible for the violence, Ranneberger said.
Ethnic violence and protests have escalated since the disputed December 27 presidential election between Kibaki and Odinga. Kibaki claimed victory and took the oath of office shortly after results were announced, and international monitors have criticized the election as flawed.
Since then, at least 863 people have been killed and 261,000 forced from their homes, the Kenyan Red Cross says. Kenya had long been regarded as peaceful and relatively prosperous, but the political violence that erupted after Odinga's party declined to recognize the election results has taken on ethnic overtones.
Kibaki's tribe -- the Kikuyu -- has dominated Kenyan politics and commerce since the country gained independence in 1963. Odinga belongs to the Luo tribe.
The two men met face-to-face on Wednesday in a meeting Annan facilitated.
Nonetheless, the bloodletting has shown no sign of abating, said Anthony Mwangi of the Kenyan Red Cross.
"The violence is not stopping," he said. "It could reach a point where it is difficult to reverse."
Meanwhile, the U.S. State Department on Thursday announced a travel alert for Kenya, advising U.S. citizens to avoid travel to "the cities of Kisumu, Nakuru and Naivasha, and defer all non-essential travel to the remaining portions of Nyanza, Western, and Rift Valley provinces" due to the post-election violence.
"Road travel in western Kenya remains unsafe," the travel alert says. "Sporadic illegal road blocks by gangs or criminal elements may make travel possible only with police-escorted convoys. American citizens are strongly reminded that even demonstrations intended to be peaceful can become violent. Americans should therefore avoid all demonstrations, protests and large public gatherings."
The State Department also announced that it had authorized the relocation of all non-emergency U.S. personnel and diplomats' family members from Kisumu to Nairobi.
On Wednesday Assistant U.S. Secretary of State Jendayi Frazer described the violence as "ethnic cleansing," but State Department spokesman Sean McCormack stressed that was her personal opinion and not the official U.S. position.
Nonetheless, the State Department was closely monitoring the situation for "any incidence of atrocities," McCormack said.
In addition, the United States was reviewing the hundreds of millions of dollars of humanitarian aid it sends to Kenya. E-mail to a friend
CNN's Zain Verjee and Elise Labott contributed to this story