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. Same-sex relationships are illegal in the country.

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."