Zambia has arrested three former managers at a state-owned company for suspected corrupt practices involving over 300-million kwacha ($18.75-million), which forced donors to temporarily freeze aid, anti-graft authorities said on Thursday.

Their arrest follows that of former foreign minister Joseph Malanji, who was taken into custody on Tuesday for alleged possession of property suspected to be proceeds of crime.

Britain, Finland and Sweden withheld nearly $34-million in aid to Zambia's social cash welfare and education sectors in 2018 because of concern over financial mismanagement.

Following his election in August, President Hakainde Hichilema vowed to step up the fight against graft and recover state assets allegedly stolen under the previous government, which also left Zambia a multi-billion dollar debt crisis that has forced it to seek help from the IMF.

Zambia's anti-corruption commission and the anti-money laundering unit said they arrested former Zambia Postal Services Corporation Postmaster General Macpherson Chanda, 47, and two others for corruption committed between January 2017 and December 2018.

Chanda did not respond to a request for comment.

"The trio in their capacities as postmaster general, director of finance and director of operations, respectively, are said to unlawfully diverted social cash transfer funds amounting to 335,108,834 kwacha," the joint statement said.

The three were released on police bond and are to appear in court soon.

A Zambian court in May jailed a former cabinet minister for two years in a corruption case involving the same social welfare funds.