Abe Sano, head of the Commercial Bank of Ethiopia (CBE) said on Tuesday about $10m has been recovered.

Thousands of customers returned the cash voluntarily. Mr Sano warned those who had not will face criminal charges.

Most of the money was withdrawn by university students.

On 16 March, news of the glitch spread across universities - largely via messaging apps and phone calls - and long lines were seen at campus cash machines.

The bank has not never explained exactly what the problem was, but the CBE said the glitch was not the result of a cyber-attack and that customers should not be worried as their personal accounts were intact.

At least three universities released statements advising students to return any money not belonging to them that they may have taken from the bank.

In an interview with the BBC's Newsday programme last week Mr Abe said the CBE was already in the process of reporting customers to the police.

"There is no way that they can escape because they are digital [transactions] and they are our customers. We know them. They are traceable and they are legally accountable for what they did," he said.

Initial reports said that more than $40m was lost in the technical glitch.

A CBE employee told the BBC it was harder to find money transferred to other banks than to trace sums moved to another CBE account.

A total of 490,000 transactions were made before CBE realised there was a problem.

More than 38 million people hold accounts at the CBE, which was established 82 years ago.