Kenyan opposition leader Raila Odinga is calling for a strike to support his claim to the presidency while accusing the ruling party of "spilling the blood of innocent people", despite growing pressure on him to concede election defeat.
There have been at least 24 deaths in election-related unrest so far, the Kenya Red Cross said on Saturday, including that of a nine-year-old girl.
The election commission on Friday declared incumbent Uhuru Kenyatta winner of the presidential poll by 1.4 million votes. International observers said Tuesday's election was largely fair but Mr Odinga disputes the results, saying it was rigged. He has not provided documentary evidence.
"Jubilee have spilt the blood of innocent people. Tomorrow there is no work," Mr Odinga told a crowd of around 4000 cheering supporters, referring to the ruling party.
There have been deadly clashes between police and civilians in his stronghold areas. Presidential spokesman Manoah Esipisu blamed the bloodshed on protesters.
"The violent protests are unlawful," he said in a statement on Sunday.
Reuters reporters have seen police repeatedly fire tear gas and bullets to disperse crowds of people in slums. Police have also detained and physically attacked journalists.
By Sunday the violence had largely abated, to the relief of Kenyans who feared a repeat of the carnage that followed 2007's disputed election, when 1200 people died and 600,000 were displaced.
Some Mr Odinga supporters are convinced that victory was stolen from them in the 2007 and 2013 polls, both marred by irregularities and problems. Mr Odinga contested both, and lost, and his supporters say they will not back down this time.
Diplomats and regional leaders are urging Mr Odinga, a former political prisoner, to concede. Their united stance leaves the 72-year-old opposition leader isolated if he chooses to maintain the allegations of election fraud and proclaim himself president.