The Kenyan election commission's computer systems and vote-tallying databases were not compromised at any point during yesterday’s vote, its chief executive has said.

It comes after Kenyan opposition leader Raila Odinga said the computers had been hacked and fake results were posted online to show President Uhuru Kenyatta with a strong lead in what he described as a "massive" fraud.

Earlier, the election commission said the vote was free and fair and that it was investigating whether or not its computer systems and vote-tallying database had been compromised. It said it had not had a problem with its passwords.

Mr Odinga's statement, which is based on his belief that a murdered election commission technician had his identity stolen, raised concerns of unrest over the results in Kenya.

The country is East Africa's leading economy and a regional hub.

Around 1,200 people died and 600,000 were displaced in ethnic violence after a disputed election in 2007.

Speaking at a news conference, Mr Odinga urged his supporters to remain calm but added: "I don't control the people".

His deputy Kalonzo Musyoka struck a similar tone and said the opposition might call for "action" at a later date. He gave no details.

Shortly after Mr Odinga spoke, police fired teargas to scatter a group of 100 supporters in the western city of Kisumu, an opposition stronghold.

The unarmed men had been chanting "No Raila, no peace".

They later used live rounds to disperse another group, while a pro-Odinga protester was shot dead by police in a Nairobi slum, witnesses said.

As of 8pm, provisional results from the election commission website put Mr Kenyatta in front with 54.3% of votes counted to 44.8% for Mr Odinga - a margin of 1.4 million ballots with 97% of polling stations reported.

Mr Odinga published his own party's assessment of the count on Twitter, saying he had 8.1m votes against 7.2m for Mr Kenyatta but published no supporting documentation.

As of 2.30pm Irish time, the election commission website put Mr Kenyatta in front with 54.4% of votes counted to 44.8% for Mr Odinga - a margin of 1.4 million ballots with 96% of polling stations reported.

Mr Odinga published his own party's assessment of the count on Twitter, saying he had 8.1m votes against 7.2m for Mr Kenyatta but published no supporting documentation.

Despite its multimillion dollar electronic voting system, the crucial evidence on voting comes from the paper forms signed at each of the country's 41,000 polling stations.

Results in each polling station are recorded on a form - known as 34A - that observers from each party must sign. These are then scanned and sent to the election board for posting online.

The measure is designed to ensure the elections cannot be rigged and parties can cross-check results.

This morning, the commission said it had received 28,000 forms and was working to make all forms public.

The Kenya Human Rights Commission, a well-known non-governmental organisation, said it had discovered some discrepancies between provisional results on the election commission website and the paper forms.

It cited five examples, including a polling station in western Nandi county where the electoral board's website recorded 439 rejected votes but the paper form only showed four.

Mr Odinga ran in Kenya's last two elections and lost, blaming vote rigging following irregularities at both polls.