President Kibaki's anti-corruption campaign has borne some fruit

The four are said to have been involved in the awarding of a contract for passport-making equipment.

The deal was initially said to be worth $10m, but the contract was subsequently awarded without a tender to the French company, which had asked for $34m.

The contract was suspended last week, pending an official inquiry.

The company, Francois-Charles Oberthur Fiduciaire, has denied any wrongdoing.

Kibaki's fight

Those suspended include the most senior officials from the finance and home affairs ministries, as well as the director of the government information technology service and a senior state lawyer involved in the project.

President Mwai Kibaki has pledged to make the fight against corruption a key part of his programme.

Under former President Daniel arap Moi, Kenya became notorious for bribery, leading to a suspension of lending from the International Monetary Fund.