A prominent Malawian banker has been arrested in connection with a suspected attempt to bribe a panel of five judges presiding over the country's presidential election vote-rigging case.

The Anti-Corruption Bureau (ACB) said it arrested Thomson Mpinganjira on Wednesday after receiving a complaint on December 8 alleging that some people were attempting to bribe the judges of the Constitutional Court.

"Dr Mpinganjira will be taken to court after the ACB has recorded a statement from him," said ACB spokesperson Egrita Ndala.

Malawian opposition parties are challenging the state electoral commission's May 27 declaration of President Peter Mutharika as the victor despite complaints of irregularities, including result sheets with sections blotted out or altered with correction fluid.

The small, landlocked country has since been plagued by protests and demands for Mutharika to resign.

Mutharika beat opposition candidate Lazarus Chakwera by 159,00 votes - a lead of just over three percentage points.

Mpinganjira spent the afternoon at the ACB offices in Blantyre. Hundreds of people gathered and chanted "Thief! Thief!" as he was being whisked away by tight security to a police station.

Mpinganjira, an accountant, is the former founding chief executive of the Malawi Stock Exchange (MSE). He left to open private First Discount House (FDH) which later evolved into a bank and has a nationwide branch network.

He is also a board chairman of state-run power utility Escom.

Many people in Malawi have said he is connected to the governing party, but he has always denied any links.

His lawyer Patrice Nkhono told Reuters news agency by telephone that his client has no comment to offer.

The Constitution Court is expected to announce its ruling between January 27 and February 3, the High Court's Registrar, Agnes Patemba, was quoted as saying by Malawi's Zodiak Radio on Wednesday.