A Zimbabwean journalist who reported that Grace Mugabe, the first lady, donated used clothing including underwear to supporters of the ruling Zanu-PF party has been detained and charged with causing a criminal nuisance.

Kenneth Nyangani, a reporter from NewsDay newspaper, was held in a police cell for 18 hours after his arrest on Monday night, his lawyer, Passmore Nyakureba, told the Guardian.

International human rights organisations have called for Nyangani’s release and accused Zimbabwean authorities of seeking to intimidate and harass journalists in the former British colony.

“The arrest … is a deliberate tactic to harass and intimidate him and other journalists in order to deter them from doing their work,” said Cousin Zilala, executive director of Amnesty International Zimbabwe.

Tensions are rising in Zimbabwe as the economy deteriorates and a vicious struggle to succeed the 93-year-old president Robert Mugabe, in power for more than 35 years, intensifies.

The main contenders to take power when Mugabe dies or steps down are his wife and Emerson Mnangagwa, a vice-president who has significant support within the country’s powerful security establishment.

The first lady is deeply unpopular with Zimbabweans, who have been incensed by reports of her extravagant spending.

The 53-year-old recently bought a $400,000 (£300,000) Rolls-Royce and has invested heavily in South African real estate, Zimbabwean media reported this week.



Footage of one of her sons taking delivery of two top of the range Rolls-Royce cars last month prompted outrage.

Nyakureba said his client, who is due to appear in court on Wednesday morning and could face up to six months in prison and a $200 fine, was standing by his story “100%”.

“This reaction from the authorities is just because the first lady is involved. They want people off her back. She has been receiving a lot of negative reports in the newspapers and they want to improve her image,” he said.

In August, Grace Mugabe was accused of assaulting a model with an electric cable in an upmarket neighbourhood in South Africa’s commercial capital, Johannesburg. She was controversially granted diplomatic immunity after the incident and allowed to leave South Africa despite an ongoing police inquiry.



She denies all wrongdoing and says the model, Gabriella Engels, attacked her with a knife.

The first lady did not accompany her husband on a visit to South Africa this week. Speaking in Pretoria on Tuesday, Robert Mugabe sought to smooth any ruffled diplomatic feathers, telling Jacob Zuma, the beleaguered South African president, that their countries were bonded by the efforts they had made together against repression.

The Mugabes in Harare. Grace Mugabe has positioned herself as a possible successor to her 93-year-old husband. Photograph: Reuters

“We are … one people, one revolution, one struggle, one future”, Mugabe said, before hitting out at “those who wanted to undermine our economies” through the use of information technology and calling for unity in the face of the challenge of climate change.

Mugabe and other Zanu-PF officials have repeatedly blamed economic troubles in Zimbabwe on sanctions imposed by the west after a wave of repression 15 years ago.

In recent weeks, an economic crisis has gathered momentum. Fears of a return of hyperinflation seen in 2008 have led to panic buying and rocketing prices, while confidence in the parallel “bond note” currency, launched by the government nearly a year ago, has collapsed.

Usually busy neighbourhood garages in the Zimbabwean capital, Harare, have been left without fuel.

The currency crisis a decade ago wiped out personal savings, left shops empty and made it all but impossible to buy fuel or groceries. Inflation peaked at 89.7 sextillion per cent before the national Zimbabwean dollar was abandoned in favour of the US dollar. The economy never recovered.

Peter Mutasa, president of the Zimbabwe Congress of Trade Unions, said there was a shortage in basic commodities.



“The situation has been triggered by lack of confidence in the bond notes. We are being driven to barter for goods because there is no hard currency in the banks,” he said.

Shops regularly offer several prices for goods – an illegal but common practice. One seller of pumps in Bulawayo, the southern city, said prices were between 25% and 50% higher for those paying with bond notes.

Further economic breakdown could reignite protests that shook Mugabe’s regime last year, but ministers have denied any crisis.

“There are economic indicators to convince us that our economy is actually recovering in terms of mining, agriculture, manufacturing as well as tourism,” the industry minister, Mike Bimha, said in an interview this week.

“Our economy is on the recovery path and we just have to apply some more pressure for us to be able to turn around.”