Kenyan police have instructed some 20 leading figures, including officials politicians, not to leave the country, as corruption investigations continue.
President Kibaki has urged Kenyans to be patient
The 20 are allegedly linked to the "Goldenberg" affair, in which millions of dollars were paid for non-existent exports of gold and diamonds.
One of those ordered to deposit his passport is George Saitoti, who on Monday resigned as education minister.
The government is also threatened by a separate corruption scandal.
Meanwhile, some 80 MPs have urged President Mwai Kibaki to sack his deputy, Moody Awori, who is accused of involvement in the "Anglo Leasing" affair, which has cost two ministers their jobs this month.
They have threatened to stage street protests on Friday unless their demands are met.
Mr Kibaki was elected in 2002 on a pledge to fight the corruption which had characterised the previous administration of Daniel arap Moi, who was in power during the Goldenberg affair.
Mr Kibaki's former anti-corruption advisor John Githongo has accused him of doing nothing over the Anglo Leasing scam.
The 20 figures linked by the police to Goldenberg have also had their firearms licences cancelled and been ordered to surrender their weapons.
As well as Mr Saitoti, they include Mr Moi's sons, Gideon and Philip, chief suspect Kamlesh Pattni and other MPs and officials.
Mr Saitoti has denied any wrongdoing.
A report on the Goldenberg affair was handed to Mr Kibaki last week.
Mr Kibaki has urged Kenyans to be patient while the investigations continue.
The resignation of Energy Minister Kiraitu Murungi was announced on national television by President Mwai Kibaki at the same time as that of Mr Saitoti.
Mr Murungi had vowed to stay on last week after the BBC obtained a tape allegedly of him trying to persuade Mr Githongo to hold back on his investigations, while Mr Murungi was justice minister.
"I have not been involved in any corruption," he said on Tuesday, blaming his problems on political problems within the ruling Narc coalition.
Mr Githongo's report has cost two ministers their jobs
"The media has made me the most vilified and hunted person in Kenya."
The BBC's Karen Allen in Nairobi says Mr Murungi is a key member of Mr Kibaki's inner circle. He vowed to return to the political stage.
The Anglo Leasing affair prompted a delegation of Kenyan MPs to fly to the UK, where Mr Githongo is in exile, to quiz him about his allegations.
Mr Githongo said he was "reassured" after meeting MPs over the weekend.