By Andrew Harding in Nairobi BBC East Africa correspondent

Moi stepped down last year after 25 years in power

The unprecedented move is part of a wider investigation into a banking scandal which saw large sums of public money disappear.

This has never happened before in Kenya - a former president ordered to submit to police questioning.

Kenyan investigators want to ask Mr Moi about Euro Bank.

It went bust in February after it was discovered that almost $14million worth of public money had vanished from its accounts.

Five senior officials have already appeared in court.

At least one has said he was acting on the direct orders of President Moi when he transferred state funds to Euro Bank before its collapse.

At the moment Mr Moi is not being accused of any wrongdoing but investigators are keen to hear his version of events.

Unimaginable

This situation was unimaginable only a few months ago.

Kibaki campaigned against corruption

President Moi stepped down in December after a quarter of a century in power.

He has acknowledged that corruption was a serious problem during his rule but has strenuously denied any personal involvement.

His son, Gideon Moi, is being investigated over the Euro Bank scandal.

He has accused the new government of launching a political witch-hunt.

Privately senior officials in the new government have said they have no intention of hounding Daniel arap Moi following his retirement.

Kenyan democracy has more to gain from a peaceful transition, said one, than from delving into the former president's past.

Nonetheless, the new government has launched a series of probes into high-level corruption.