Stone-throwing protesters clashed with police in Kenyan cities on Wednesday during a second round of demonstrations in less than a week, called by the main opposition leader against a raft of tax hikes.

Police officers fired teargas to disperse protesters in the capital Nairobi, the port city of Mombasa and several other towns, according to Reuters reporters and footage aired on Kenyan television stations.

"We have ventured out on our own accord," said Ibrahim Stanley, a protester in Nairobi's informal Kibera settlements. "We are out here because we are tired."

Intense clashes took place on the expressway connecting Nairobi to the main airport, where protesters lit bonfires and toppled fencing. The expressway said toll services had been halted at three stations.

At least six people were killed last Friday during protests against the taxes, which are contained in a finance bill signed into law by President William Ruto last month.

Kenya's High Court ordered the suspension of implementation of the legislation pending a legal challenge, but the government has raised petrol prices anyway.

Opposition leader Raila Odinga, who called for the protests, was due to address supporters in Nairobi later on Wednesday, a spokesperson said. Odinga finished runner-up in the last five presidential elections, including losing to Ruto last year.

Odinga led a series of protests earlier this year against the high cost of living and alleged election irregularities, demonstrations that repeatedly degenerated into unrest. That prompted civic leaders to warn against a return to the ethnically-charged violence that has plagued Kenya in the past.

Ruto's government says the tax hikes, which include a doubling of the fuel tax and introduction of a levy to fund affordable housing, will raise an extra 200-billion Kenyan shillings ($1.42-billion) a year and are needed to deal with growing debt repayments and to fund job-creation initiatives.

The opposition says they will deepen the suffering of Kenyans at a time when many are already struggling with high prices of basic commodities such as maize flour. ($1 = 141.2000 Kenyan shillings)