Kenyans have expressed outrage over the detention of a software developer who created a tool to help people oppose the government's annual finance bill because of fears that it will raise the cost of living.

Rose Njeri was detained on Friday after police raided her home in the capital, Nairobi, and seized electronic devises, activists said.

Police and the government have not yet commented on the detention of the mother of two.

Mass protests broke out last year after the government proposed tax hikes, forcing President William Ruto to withdraw the 2024 finance bill.

The bill outlines the government's spending priorities for the next financial year, and how it intends to raise income.

At least 50 people were killed and dozens were abducted in a security force crackdown to end the protests that broke out last year.

Law Society of Kenya (LSK) president Faith Odhiambo told the BBC Newsday radio programme that Ms Njeri's detention was a "recurrence of dictatorship".

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On Sunday, a group of activists gathered outside a police station in Nairobi, where the software developer is being held, to demand her release.

Ms Odhiambo said that Ms Njeri - whom activists visited in prison - was "crestfallen" because with Monday being a public holiday, she had not yet been brought to court.

Attempts to get her released on bail had failed, she added.

"This has always been a government way of oppressing, intimidating and suppressing citizens because they know the courts don't sit over the weekend – and now we have a public holiday," Ms Odhiambo said.

Boniface Mwangi, one of the activists who had visited Ms Njeri in custody, said she told them that police had ransacked her house and taken her phone, laptop and hard drives.

He said she was worried about her two children.

"Imagine having to tell her children that she's in jail for developing a website that eases public participation for Kenyans who want to submit their proposals on the 2025 budget," he said on X.

Ms Njeri was detained after sharing a link to a site that flagged clauses in the bill that she said would lead to the cost of living escalating. It also allowed people to email parliament, calling for the bill to be withdrawn.

She also raised concern that a proposal to amend tax procedures, allowing the tax authority to access personal data without a court order, could undermine privacy rights.

The new finance bill replaces the zero-rated tax provision on essential commodities with tax-exempt status.

Zero-rated goods are taxed at 0%, and suppliers do not charge value-added tax (VAT) to customers but can still claim input VAT on the materials used in producing these goods.

Tax-exempted goods are also not subject to VAT but suppliers cannot claim back input VAT, leading to higher prices for consumers or reduced profit margins for businesses, economists and activists say.

Finance minister John Mbadi recently admitted that tax-exempt goods may be "slightly more expensive" but explained that the move was necessary to close tax loopholes.

He said the government had determined that traders do not pass the zero-rating benefit to consumers, while some make "fictitious and fake" claims for refunds.

Mbadi is scheduled to present the government's spending and tax proposals in parliament next week.

Last week, Ruto apologised to Kenyan youth for "any misstep" in dealing with them since he took office in 2022.

Last month, he said that all the people who had been abducted after last year's protests against tax hikes had been "returned to their families".