Kenya resorted to choppers to fly officials carrying results from this week's presidential poll to the capital, let down by new technology aimed at avoiding the violent disputes that led to 1,200 deaths after the vote five years ago.

The snail-paced release of results, after the electronic system used to transmit numbers direct from polling stations to a central tallying centre failed, has deepened voter anxiety and may undermine prospects for such systems in other African votes.

Past elections in Kenya have been dogged by "ghost" voters, stuffed ballot boxes and rigging at the final tally, all of which have plagued polls across sub-Saharan Africa for decades, as corrupt leaders turned a blind eye to popular will.

In Kenya's presidential vote in 2007, opponents cried foul when now-outgoing President Mwai Kibaki won a second term, plunging east Africa's biggest economy into weeks of mayhem.

This time, Kenya was determined to deliver a credible, transparent process.

"I'm almost embarrassed that it did not work," Bitange Ndemo, the information and communication ministry's top civil servant, told Reuters.

Computer servers used by the election commission to handle the incoming data were overwhelmed, Ndemo said.

Although Kenyans appreciated the honest intentions, the delivery didn't live up to the promise.

On voting day, more than half of all the fingerprint-reading voter identification machines had broken down in polling stations across the country, forcing officials to revert to a back-up paper register.

More critically, the electronic transmission system key to the delivery of speedy results suffered crippling hitches, leading to a results vacuum that has spawned the kind of conspiracy theories the authorities were desperate to avoid.

It has also given a chance to rival candidates to sow doubt about the integrity of the tally.

As provisional results limped in via the cell-phone based transmission system, the Independent Electoral and Boundaries Commission began releasing official results as returning officers reached Nairobi from far-flung corners.

Safaricom, which provided network services, said its systems worked but the problems arose with equipment that was not its responsibility.

Deadline looming

Manual transmission was not the game plan, but the patience of voters hungry for an outcome is wearing thin, and a seven-day deadline for the results is starting to look uncomfortably close.

However, switching systems risks creating suspicion.

Kenyans want a single system they can follow and have confidence in, one local commentator said in a TV discussion.

Africa has looked to cell phones and other technologies to overcome shortcomings in infrastructure. Kenya itself has blazed a trail in mobile phone banking, a technology that has caught the eye from Asia to Latin America.

It is not the first sub-Saharan country to fall foul of such technical glitches.

Presidential elections in Ghana in 2012 were extended into a second day of polling after voter registration machines being used for the first time malfunctioned in more than 400 of the 26,000 polling stations.

"It was unfortunate. The machines broke down in many instances, or voters had indistinct fingerprints, or the machines got greasy," Mark Stevens, head of the democracy section at the Commonwealth Secretariat, told Reuters in Nairobi.

"And they had a very clear edict. No verification by machine, no vote."

Three months on, though, voters in the West African country broadly stand by technology's role in building Africa's democratic credentials, though they also want the backup of paper, pen and identity cards.

"I would not say we should abandon the use of the technology, because it enhances our trust in the system," said James Klobodzi, a 28-year-old taxi driver in Accra, Ghana's capital. "All I am saying is that it should not be the key component."

In Kenya the jury is still out.

As the delays in releasing results grow, so too do the complaints about flaws in the process, whipping up fears politicians may reject the final outcome and their supporters turn to the street.

For now, Kenyans still seem to trust the reformed election commission.

"They have started from scratch, and it needs improvements. But I think it's the future," said Krzysztof Lisek, head of a European Parliament delegation visiting Kenya.