Kenya's opposition leader Raila Odinga has called on his supporters not to go to work until he announces his next course of action after losing an election to President Uhuru Kenyatta.

Odinga's move came on Sunday after the international community appealed to him to send out a message to try to halt deadly protests.

"Do not leave your homes. Do not go to work. We will make a declaration on Tuesday on which direction we are taking," he told supporters in the Nairobi slum of Kibera, an opposition stronghold.

However, he defiantly pledged to "remove" Kenyatta's government that he said stole votes from him in August 8 elections.

"We had predicted they will steal the election and that's what happened. We are not done yet. We will not give up. Wait for the next course of action which I will announce the day after tomorrow [Tuesday]," he said.

Kibera residents climbed on to rooftops and hung off trees to catch sight of Odinga, who was speaking for the first time since Kenyatta was declared the victor on Friday in a poll Odinga claims was massively rigged.

Al Jazeera's Catherine Soi, reporting from Kibera, said: "People here said they will heed his call. They believe Odinga when he says his victory has been stolen. They will wait for more details of how exactly that happened."

Kenya's electoral commission announced on Friday that Kenyatta, 55, who has been in office since 2013, won a second five-year term with 54.27 percent of the vote. Odinga, 72, secured 44.74 percent.

READ MORE: UN calls for calm in Kenya after deadly protests

The opposition has said 100 Kenyans had been killed in clashes between Odinga's supporters and the police.

The Kenya National Commission on Human Rights said on Sunday it had counted 24 deaths and accused police of using "excessive force".

The National Police Service denied the allegations on Sunday, saying they were "unfounded and have no basis in fact and are clearly aimed at escalating tensions in the country".

There had only been six fatalities in the past two days, according to the statement published on Facebook, saying armed criminals had attacked police trying to arrest them.

The statement said police were investigating "individuals suspected of incitement to violence" and warned that "there are photos of dead bodies being attributed to police action that are fake".

Ethnic grievances

Odinga, an ethnic Luo who scored nearly 45 percent of votes to Kenyatta's 54 percent, has a huge following notably among the poor who are drawn to his platform of more equitable economic growth.

But ethnic grievance is also a key aspect of his appeal.

Three of Kenya's four presidents have been Kikuyu and the other Kalenjin, leaving Luos feeling excluded from power for over half a century.

Politics in Kenya is largely divided along tribal lines, and the winner-takes-all nature of elections has long provoked communal divisions.