The Ethics and Anti-Corruption Commission has summoned Health CS Cleopa Mailu and PS Nicholas Muraguri over the alleged fraud in the ministry.
Internal auditor Bernard Muchere and the ministry’s head of accounting Joyce Mutugi were questioned yesterday.
The EACC is investigating claims that there was double payment for goods and Sh5 billion cannot be accounted for.
The ministry, however, maintains the amount in question is Sh3.1 billion, which it says was properly used.
In a statement on Monday, Mailu said the audit was incomplete and could not be used to justify the fraud claims.
EACC chief executive Halakhe Waqo said he has requested for and received part of the documents from the ministry.
Muraguri is expected before investigators at 9am while Mailu is set to appear at the same time on Thursday.
Also lined up for questioning are head of Finance unit Peter Odundo, head of Procurement Peter Mwangi, the CEO of the Kenya Medical Supplies Authority Dr John Munyu, former head of procurement Ephantus Thigah and former head of Accounts Peter Macharia.
More witnesses, including suppliers, will be questioned.
The EACC has been investigating the ministry from around May, following revelations that a company associated with its former chairman Philip Kinisu had been awarded a tender to supply anti-malarial chemicals. Esaki Ltd delivered Pirimos Methyl 300 capsules for Sh150.1 million.
“There have been issues at the Health ministry. There has been ongoing investigations into procurement process,” EACC deputy chief executive Michael Mubea said last Friday.