* Kenyatta says election to go ahead as planned
* Odinga says election board not replaced officials
* Opposition ally calls for countrywide protests
Kenyan opposition leader Raila Odinga said on Tuesday he would not stand in a court-ordered re-run of August's presidential election that is scheduled for October 26, saying the polls would not be free or fair.
President Uhuru Kenyatta said the election would proceed as planned, despite the withdrawal of his only challenger.
Both men's announcements indefinitely prolong nearly three months of political uncertainty that has worried citizens and blunted growth in Kenya, East Africa's biggest economy and a staunch Western ally in a region roiled by conflict.
An ally of Odinga called for nationwide protests from Wednesday, raising the prospect of violent confrontations between police and protesters.
But for now there was little sign that the demonstrations could boil over into ethnic clashes. Protests and ethnic violence killed 1,200 people after a disputed 2007 presidential election.
Odinga repeated previous criticism of the election board, called the Independent Electoral and Boundaries Commission (IEBC), for not replacing some officials, who he blamed for irregularities in the August poll. Allied politicians standing alongside him called for a continuation of peaceful protests.
"Following the withdrawal of the NASA presidential candidate, the Commission and the legal team are meeting and will communicate way forward," the IEBC said on Twitter after Odinga spoke.
"There is no intention on the part of the IEBC to undertake any changes to its operations and parts of the personnel to ensure that the illegalities and irregularities that led to the invalidation of 8th of August do not happen again," Odinga told a news conference in Nairobi.
"Indications are that elections scheduled for the 26th of August will be worse than the previous one," he said. "In the interest of the people of Kenya, the region and world at large, we believe that all will be best served by (opposition alliance) NASA vacating the presidential candidature of elections."
On September 1, the Supreme Court nullified incumbent Kenyatta's win on August 8 due to procedural irregularities and ordered a new poll pitting Kenyatta against Odinga to be held within 60 days.
Call for protests
Since then, police have repeatedly used teargas to disperse small protests by the opposition demanding the election board change some officials, a call they repeated on Tuesday. Senator James Orengo, a key Odinga ally, called for countrywide protests after Odinga spoke.
"Tomorrow all over the country there are going to be demonstrations the basis will be no reforms, no elections," Orengo said.
After Odinga spoke, Kenyatta told a political rally the election would proceed as planned and he was sure he would win again, citing the majority that his party won in both houses of parliament and among the country's 47 governors.
"We have no problem going back to elections. We are sure we will get more votes than the last time," Kenyatta said in the southern town of Voi, speaking in Kiswahili in a speech carried on local television.
Murithi Mutiga, a senior Horn of Africa analyst for the global thinktank International Crisis Group, said the country looked headed for a protracted political stand-off that could rapidly escalate if there was a miscalculation by either side.
"The economy has already been battered by months and months of endless electioneering and now we see a protracted stalemate. Kenyatta will try everything to make sure the election goes ahead and Odinga might go back to the Supreme Court," he said.
"The political elites have really squandered the opportunity to consolidate the countries democracy ... both sides will inevitably try to assert themselves, including on the streets. We may see clashes between protesters and police. It looks grim."
On Monday, a Kenyan rights group said 37 people had been killed during protests immediately following the August 8 election. Almost all of them had been killed by the police.
On Tuesday, legislators from the ruling party were debating proposed amendments to the election laws, which said if a candidate boycotted an election, the remaining candidate automatically wins.
Opposition legislators boycotted the session. The draft amendments require another reading and a presidential signature before they become law.
Ruling party legislators told Reuters on Monday that the amendments were designed to head off a constitutional crisis if Odinga pulled out of the election.