Nigeria is seeking Interpol's help to arrest three suspects who allegedly stole $6.2m (£4.9m) from the central bank, using the forged signature of then President Muhammadu Buhari.

Authorities believe that the suspects conspired with Nigeria's former central bank chief Godwin Emefiele.

He is already on trial on 20 charges, including illegally receiving the $6.2m.

Mr Emefiele has denied all the charges, and is currently out on bail.

He is the most high-profile former official to be charged with corruption since President Bola Tinubu took office last May.

Prosecutors also allege that Mr Emefiele unlawfully authorised the release of the money from the central bank vault.

In a statement last December, he described the allegations as "barefaced lies told by the investigator in order to achieve his satanic agenda". He called for a "thorough and transparent investigation".

Mr Emefiele's alleged accomplices have been named as Adamu Abubakar, Imam Abubakar and Odoh Ocheme, a former central bank employee, the state-owned News Agency of Nigeria reported.

The suspects are believed to have left Nigeria, prompting the authorities to seek Interpol's help with their arrest and repatriation, the agency added.

None of the three suspects has commented on the allegations against them.

The government ordered their arrest late on Tuesday, hours after Boss Mustapha, a senior official in ex-President Buhari's administration, testified in Mr Emefiele's trial.

Mr Mustapha told the court in the capital, Abuja, that neither he nor Mr Buhari had given their signatures to approve the withdrawal of the $6.2m.

"Looking at the signature, it is a faint attempt at reproducing [former] President Buhari's signature," Mr Mustapha was quoted as telling the court by the Nation newspaper.

When shown the document used to withdraw the funds, Mr Mustapha said it "did not emanate from the office of the president", the newspaper added.

The funds were withdrawn in cash in January last year, a few months before Mr Buhari's term ended.

Prosecutors allege that Mr Emefiele falsified the document in question, which requested the central bank to issue the funds so that Mr Buhari could use them to pay foreign election observers.

Mr Emefiele was appointed as central bank governor in 2014 by then-President Goodluck Jonathan, with Mr Buhari reappointing him in 2019. He held the post until Mr Tinubu took office.