The authorities in Switzerland say they have now frozen a total of $645m in bank accounts linked to the late Nigerian military ruler, Sani Abacha.

This is by far the largest sum frozen by the Swiss in cases involving former dictators accused of enriching themselves at their countries' expense.

The total includes $95m frozen in recent days in the Swiss banking centres of Zurich and Geneva.

The Swiss police have agreed to a Nigerian request for legal help in recovering the money.

The Nigerian government says General Abacha, who died in 1998, illegally sent abroad about $2bn in total.

Last month the Swiss authorities opened a money-laundering inquiry after freezing $550m in bank accounts belonging to General Abacha, members of his family and his associates.

Nigeria has now also begun taking legal steps in other European countries, including the United Kingdom, France and Germany, to try to recover its plundered assets.

General Abacha, his family and associates are accused of systematically plundering Nigeria's central bank during his four years in power.

Money laundering

The accounts under scrutiny belong to the general himself, to his former security advisor Alhaji Ismaila Gwarzo, former government minister Abubakar Attiku Bagudu, as well as a number of unidentified Nigerian businessmen and companies.

The military leader died suddenly in 1998, and political reforms initiated by his successor led to the restoration of democratic rule in 1999.

Switzerland has often been criticised as a money-laundering centre, with several former foreign rulers currently under investigation.

A law which came into effect last year obliges banks to report and freeze suspicious accounts.

The Swiss bank accounts of the late President of Zaire, Mobutu Sese Seko, are still frozen pending legal action.

Economic reform

Meanwhile, in Nigeria, President Olusegun Obasanjo has proposed measures aimed at reviving the economy which was brought close to collapse under years of corrupt rule.

The president wants to reform the country's customs duties in an effort to revive the flagging industrial sector.

The president's proposals - which include reducing custom duty rates on most raw material imports and increasing the rate on imported finished products - are presented in the new budget for the year 2000.

The budget is yet to be approved by parliament.

The proposals also include a plan to generate at least 200,000 new jobs spread across all sectors of the economy.