Attorney-general Amos Wako blamed the delay on the country's judicial system.
The Anglo Leasing affair involved $100m contracts awarded to a phantom British firm, Anglo Leasing Finance.
The Anglo Leasing contracts were for sophisticated passport equipment, navy ships and forensic science laboratories for the police force, which have never been supplied.
'Itching to prosecute'
Mr Wako told the BBC that the country's High Court had passed a ruling blocking the investigation after some suspects challenged the legality of the SFO's involvement.
"I understand the position of the SFO. They have been waiting for some time because of some legal obstacles."
He said the government had appealed against the ruling.
"Until the appeal is successful, investigations are stopped," Mr Wako said.
Mr Wako, who has been the country's attorney-general for 17 years, admitted that he has never prosecuted any ministers for corruption although he believes that some have stolen public funds.
"I am itching to prosecute, I can tell you that," he said.
The SFO began its probe in July 2007 after receiving a request for the Kenya Anti-Corruption Commission (KACC), and was investigating offshore accounts in the British tax havens of Jersey and Guernsey.
Three ministers, including the then Finance Minister David Mwiraria, resigned in 2006 to pave way for investigations, although two were later reinstated.
Mwalimu Mati, the head of an anti-corruption watchdog, accused the government of conducting a cover-up of the scam.
"The government has now declared that it truly is not interested in fighting corruption and indeed is engaging now on a daily basis in corruption scandals which ultimately may dwarf Anglo Leasing," he said.
The SFO has conducted several investigations into international corruption cases, including allegations that a British arms company, BAE Systems, paid bribes to secure deals in Saudi Arabia and Tanzania.
It was criticised for dropping its Saudi investigations, saying these could jeopardise national security.
