Kenyans on Thursday ignored a call by the opposition to boost anti-government protests, although isolated clashes flared in the capital between police and stone-throwing demonstrators.

Police fired tear gas and live rounds at protesters in Nairobi's Kibera slum, an opposition stronghold, but no violence was reported elsewhere in contrast to earlier demonstrations.

Veteran opposition leader Raila Odinga called for three days of demonstrations this week, with Wednesday's protests claiming six lives according to Amnesty International's Kenya chapter, which said it had cross-checked the toll with victims' families.

Since March, 20 people have died in the demonstrations, according to figures released by the government and hospitals, the unrest has alarmed Kenyans and the international community alike.

President William Ruto on Thursday repeated his call for a stop to the demonstrations, saying they were "not a solution to the problems of Kenyans".

Opposition leader Odinga says Ruto's government is illegitimate and responsible for a cost-of-living crisis and had urged Kenyans to show up in large numbers on Thursday, tweeting: "The voice of the People must be heard."

But no major demonstrations were reported on Thursday, apart from skirmishes in Kibera, where police clashed with protesters, while some residents armed with sticks stood guard to prevent burglaries.

"Yesterday, five shops were looted in this area, we are here to avoid that  happening today, we are tired of it," said Jacob Anyango, 45.

Schools in Nairobi and the opposition bastions of Kisumu and Mombasa reopened, with the interior ministry assuring Kenyans that it had taken "adequate measures to guarantee the safety and security of learners".

Nairobi's business district, which was largely shuttered on Wednesday, also went back to work, with stores reopening.

"The shop was closed yesterday because there was a lot of tension, and we felt people can take advantage of the situation to loot," said mobile phone salesman Peter Wangui.

"We feel today is safer... but it is not as busy as it used to be, the protests are hurting businesses," the 24-year-old told reporters.