Zambia wrestles with devastating drought caused, experts say, by a dramatic shift in weather patterns.
BBC News, Lusaka
Controversial Zambian musician and anti-corruption campaigner Fumba Chama has been freed on bail following his arrest on Saturday for addressing a youth meeting.
The musician, who performs under the name Pilato, told the BBC he would continue with his activism.
His arrest showed there were "scared little men and women somewhere who are benefiting from our corrupt systems," but he would not be "intimidated" into giving up the campaign for greater transparency and accountability, Chama said.
Pilato has charged with holding an "unlawful assembly" in the southern city of Livingstone on Saturday.
His colleagues - Laura Miti and Bornwell, who were detained while trying to secure his release - have also been freed on bail.
Ms Miti tweeted:
Under the Public Order Act, organisers of public meetings are required to inform the police in advance about their plans
Police usually block meetings deemed to be of a political nature, citing inadequate manpower to police the gatherings.
Pilato, whose music is a fusion of rap and hop, is a social commentator through his music.
He has been detained before and in 2017 he fled to South Africa after receiving death threats for his song Koswe Mumpoto (Rat in the Pot), which was interpreted as being critical of Mr Lungu and his ministers.
BBC World Service
Opposition politicians in Zambia have condemned the arrest of a prominent musician and anti-corruption campaigner.
Police say Chama Fumba, who performs under the name Pilato, was arrested on Saturday for addressing an unauthorised rally in the southern city of Livingstone.
Two human rights activists who travelled from the capital, Lusaka, to Livingstone to secure his release on police bond were detained on arrival. All three are still in police custody.
If convicted of unlawful assembly, Pilato faces up to five years in jail.
He was arrested in 2015 for a song that was deemed to be critical of President Edgar Lungu.
Zambia is suspending a 15% export duty on all precious and semi-precious stones except diamonds, according to a government document posted on a South African mining company's website.
The new rule comes into effect from the beginning of 2020.
The duty, which came into effect at the start of this year, has damaged the profits of the mining companies and was one of several taxation measures that have been a source of conflict with the government, the Reuters news agency reports.
Mining companies have to pay a royalty tax and a turnover tax, Mining Weekly reports.
On its website, South African miners Gemfields said that it was "pleased to announce" that the export duty had been suspended.
In the latest twist in a diplomatic spat between Zambia and the US, the southern African nation's foreign minister has called the US ambassador to Lusaka "unprofessional" and accused him of threatening to withdraw aid.
It follows President Edgar Lungu's request for the US to withdraw its ambassador, after the diplomat criticised the jailing of two men for being in a gay relationship. Zambia is a socially conservative country and homosexual acts are illegal.
Ambassador Daniel Foote had said last month that he was "horrified" when a judge sentenced the men to 15 years in prison.
Zambia's foreign minister was also angered by the US diplomat saying Zambia's current government "wants foreign diplomats to be compliant with open pocketbooks and closed mouths".
Zambia's Foreign Minister Joseph Malanji said at the time that it was "tantamount to questioning the Zambian constitution".
"You cannot ask a government to make a decision at gun point – 'because we are giving you aid, we want you to do this' - you can't," Mr Malanji told BBC Focus on Africa on Monday.
"We find it funny for an ambassador who is accredited to Zambia, who knows the dos and don’ts of the laws in Zambia, to have a press briefing condemning the judiciary.
"We do not expect to have an ambassador to Zambia to have tantrums."
BBC News, Lusaka
Zambia's cabinet has approved the cultivation, processing and export of cannabis for economic and medicinal purposes.
Chief government spokeswoman Dora Siliya confirmed in a statement that the decision had been made at a special cabinet meeting on 4 December.
The next step will be for legislation to be drafted and presented to parliament for its approval. No date has been set for this yet.
In 2017, Lesotho became the first African country to legalise the cultivation of marijuana for medicinal purposes.
Zimbabwe has also since legalised its cultivation - and last year South Africa's Constitutional Court legalised the growing and smoking of marijuana for personal consumption.
Zambia's President Edgar Lungu says his government has asked the US to withdraw its ambassador, after the diplomat criticised the jailing of two men for being in a gay relationship.
Daniel Foote said he was "horrified" last month when a judge sentenced the men to 15 years in prison.
He called on the government to review the case.
Mr Lungu said he did not want people like Mr Foote in the country.
He said he was waiting for a response from Washington, in a row which began three weeks ago. The US embassy has not replied.
Homosexual acts remain illegal in Zambia under British colonial-era laws.