Kenya on Wednesday braced up for a new round of protests despite the government warning it would not tolerate further unrest after earlier demonstrations turned violent with more than a dozen people killed.

Police were seen using live rounds and tear gas to disperse stone-throwing protesters during those rallies, drawing accusations of heavy-handedness from civil society groups.

This is the third time this month that opposition leader Raila Odinga has staged mass rallies against a government he says is illegitimate and responsible for a cost-of-living crisis.

The government has said it would not allow lawlessness to go unchecked, while police described the demonstrations as "nothing but a threat to national security".

The opposition has vowed three straight days of protests against President William Ruto's government, alarming the international community which has joined calls for a political solution to the crisis, that has seen schools closed and shops shuttered in Nairobi and other cities, where protesters have been urged to bang pots and march in an act of defiance.

"We call on Kenyans to put on their old armour of courage and work to take their country before this dictatorship takes firm roots," the Azimio opposition alliance said Tuesday.

Similarly, Interior Minister Kithure Kindiki said on Tuesday that national security agencies have deployed all available resources to maintain order.

"Anyone planning to unleash violence on Kenyans is hereby warned to cease and desist," Kindiki added.

Ruto, a former vice president, rose to the top job after winning a narrow election victory last August over Odinga, who claimed the vote was "stolen".

He took office as Kenya's economy reeled from debt and soaring inflation, and was criticised for raising taxes despite campaigning to bring prices down.

Kenya is seen as a stable democracy in the often-turbulent East Africa region, and 13 Western nations issued a joint statement on Tuesday expressing concern over the violence in recent demonstrations.

"We urge all parties to table their concerns through a meaningful dialogue and resolve their differences peacefully to build the nation together, ensuring no further loss of life," the foreign missions said.