What you need to know:
- Nairobi police chief Adamson Bungei said on Sunday that police received requests to hold two demonstrations only late Saturday and early Sunday, when normally three days' notice is required for public rallies.
Kenyan riot police were out in force Monday for a day of action called by the opposition to protest the country's cost of living crisis, despite a ban on the demonstrations.
In one part of Nairobi's biggest slum Kibera, demonstrators set tyres alight, while several youths were arrested at one of the venues for the demonstrations in the capital, AFP journalists saw.
Opposition leader Raila Odinga, who narrowly lost last year's presidential election to William Ruto, has vowed that the rallies will go ahead.
"I want Kenyans to come out in large numbers and show the displeasure of what is happening in our country," he told his supporters Sunday.
Kenyans are suffering from surging prices for basic necessities, as well as a sharp drop in the local shilling against the US dollar and a punishing drought that has left millions hungry.
"Day of showdown," was the headline in Kenya's The Standard newspaper on Monday.
Nairobi police chief Adamson Bungei said on Sunday that police received requests to hold two demonstrations only late Saturday and early Sunday, when normally three days' notice is required for public rallies.
"For public safety, neither has been granted," he said.
Interior Minister Kithure Kindiki also issued a statement on Sunday warning that anyone inciting public disorder or disturbing the peace would be prosecuted.
Skyrocketing' cost of living
Roads were quieter than normal in Nairobi on Monday and many businesses were shut ahead of the demonstrations, with some employers telling their staff to work from home.
Odinga said he called the demonstrations to protest the "skyrocketing" cost of living and the "stolen" election in August last year.
"Since Mr Ruto was sworn in six months ago, he has continued to run the country with a lot of contempt," he said, highlighting the high cost of basics such as fuel, cooking oil, school fees and electricity.
Odinga, leader of the Azimio la Umoja party, has long protested that the August election was fraudulent and denounced Ruto's government as "illegitimate".
According to official results, Odinga -- who was making his fifth bid for the presidency -- lost to Ruto by around 233,000 votes, one of the closest margins in the country's history.
The Supreme Court dismissed his appeals, with its judges giving a unanimous ruling in favour of Ruto, finding there was no evidence for Odinga's accusations.
Ruto for his part declared that he would not be intimidated by the opposition demonstrations, saying: "You are not going to threaten us with ultimatums and chaos and impunity."
"We will not allow that," he said, calling on Odinga to act in a "legal and constitutional manner".