The UN human rights office (OHCHR) on Friday said it was very concerned over reports of police in Kenya using excessive force to quell protests this week which have left dozens dead and injured.

The demonstrations began over what many Kenyans view as unfair tax hikes and rising inflation in the country, according to news reports.

OHCHR Spokesperson Jeremy Laurance issued a statement condemning the violence, expressing concern over "allegations of unnecessary or disproportionate use of force, including the use of firearms, by police".

Reports estimate the number of people killed to be as high as 23, with dozens more being injured during the demonstrations.

Kenya's opposition leader reportedly called for civil disobedience and nationwide protests against the Government, amid a rising cost of living and concerns over growing inequality.

Opposition groups argue that recent tax hikes the Government says are designed to pay off debt and fund job creation, have placed an increased tax burden on families already struggling to afford basic necessities and are reportedly calling for continued demonstrations against the new policies.

Prompt investigations

"We call for prompt, thorough, independent, and transparent investigations into the deaths and injuries", said Mr. Laurence. "Those responsible must be held to account. Effective measures to prevent further deaths and injuries must be adopted."

The right to peaceful demonstration is guaranteed under Kenya's constitution, although authorities have reportedly declared the recent protests "illegal" and say they pose a threat to national security.

Right to peaceful assembly

"We call on the authorities to ensure the right to peaceful assembly as guaranteed by the Kenyan Constitution and international human rights law," said Mr. Laurence.

"We appeal for calm and encourage open dialogue to address social, economic, and political grievances, with the aim of identifying lasting solutions in the interests of all Kenyans," he added.