By Mannir Dan-Ali BBC Abuja reporter

For the first time, President Obasanjo of Nigeria has revealed details of the deal his government struck with the family of the late military ruler General Sani Abacha.

General Abacha embezzled many millions of dollars during his rule and Nigeria has been pressing the Swiss Government to return funds kept in Swiss bank accounts.

I know that the Abacha family hadn't legitimately done any work to deserve $100m

President Olusegun Obasanjo

An agreement was struck last month, under which the Abacha family keeps $100m, which the Swiss Government says "demonstrably do not derive from criminal acts".

But around $1bn will be returned to the Nigerian Government from accounts around the world.

Lawyers' fees

The agreement hammered out by lawyers from the two sides has drawn criticism because it leaves the family of the late ruler with so much cash.

In an interview published in this week's edition of Tell magazine, President Obasanjo said:

"That is one of the hardest decisions I have to make in my life because I know that the Abacha family hadn't legitimately done any work to deserve $100m."

Abacha embezzled $1.3bn in five years

The choice was either to continue with litigation - on which the Nigerian Government has already spent more than $1m - or do a deal.

In addition to the $100m, the Abacha family is free from further litigation relating to the amount covered by the agreement, the president said.

He denied rumours that Mohammed Abacha, the eldest surviving son of the late ruler, would also be freed from the criminal charges he is facing in court in Nigeria.

Mohammed Abacha has been in detention for the last two years, facing trial relating to the murder of Kudirat Abiola, wife of the late winner of the annulled 1993 presidential election.

Best deal?

In defending his decision over the matter, the Nigerian president said the deal with the Abachas is a good one.

He pointed to similar cases such as Ferdinand Marcos of the Philippines, the late Shah of Iran and the late President Mobutu of what is now the Democratic Republic of Congo, where nothing has been recovered.

At the end of the day, even if the Nigerian Government got the best deal in the circumstances, it is unlikely to satisfy those who feel that the Abachas are getting away with such a huge amount of money.

For the moment, it is unclear if this is the last to be heard of the mind-boggling amounts discovered in accounts associated with the Abacha family in bank accounts as far apart as the US, Switzerland, the United Kingdom, Luxembourg and Liechtenstein.