Zambia's Foreign Minister Stanley Kakubo has quit after he was allegedly caught on video receiving a stack of cash from a Chinese businessman.

He did not deny he was in the video.

Instead, Mr Kakubo said he was facing "malicious claims over a business transaction" and had resigned so that the government was not "distracted" by the controversy.

The video shows two men sitting by a table counting the neatly stacked cash, both US dollars and Zambian kwacha.

Their faces are not visible, but it led to a frenzy of speculation on social media that the men were Mr Kakubo and a Chinese businessman.

Some people questioned why a bank transfer had not been made and whether taxes had been paid following the transaction.

Unverified images of signed handwritten notes also surfaced on social media. One said that $100,000 had been "exchanged" between a Zambian and a Chinese mining company. Another, dated 8 July 2022, mentioned a total sum of $200,000.

In his resignation letter, Mr Kakubo did not dispute the authenticity of the video or the handwritten notes.

Instead, he said he was the victim of "malicious claims over a business transaction between my private family business and our business partner with whom we still have good relations".

He said he had resigned as a minister to ensure that the government was not "distracted" from its efforts to improve the lives of Zambians, but he would remain an MP.

"In due course, we will provide the accurate context surrounding the recent developments," the Lusaka Times news site quoted Mr Kakubo as saying.

Mr Hakainde Hichilema accepted his resignation, saying he acknowledged Mr Kakubo's "commendable work and leadership".

This is the second time that Mr Kakubo has found himself at the centre of controversy.

Last year, he was accused of receiving a bribe after he was spotted leaving the office of a Chinese-owned cement company with a briefcase.

He denied any wrongdoing, while the president defended him, saying he had received a calendar and a diary.

Chinese companies are major investors in Zambia.

The Chinese embassy said in 2022 that more than 600 Chinese businesses had invested more than $3bn in Zambia.

Mr Kakubo is the first minister forced to resign since President Hakainde Hichilema took office in August 2021.

Mr Hichilema pledged to fight corruption, but the opposition accuses him of unfairly targeting its members, which he denies.

In his response to Mr Kakubo's resignation, ex-President Edgar Lungu said he should be investigated for alleged corruption.

"I am not implying that Kakubo is guilty. All I am saying is that if there are no sacred cows in Mr Hichilema's fight against corruption, Kakubo should be investigated and if need be prosecuted...," Mr Lungu said.