The Office of the National Security Adviser (ONSA) has asked former Kaduna State Governor, Nasir El-Rufai, to submit any evidence in his possession regarding the alleged procurement of thallium sulphate to the Department of State Services (DSS) for investigation.
Thallium sulphate is a highly toxic, colourless and odourless substance capable of causing death in small doses.
In a letter dated January 30, 2026, and addressed to the National Security Adviser (NSA), Nuhu Ribadu, El-Rufai alleged that about 10 kilograms of the substance were procured by ONSA from a supplier in Poland.
Responding in a letter signed by Brigadier-General OM Adesuyi on behalf of the NSA, ONSA denied the allegation and stated that it had neither procured nor initiated any process for the purchase of thallium sulphate.
“I have the honour to present the compliments of the National Security Adviser and to acknowledge receipt of Your Excellency’s correspondence received on 11 February 2026 requesting clarification regarding the alleged procurement of approximately 10 kilograms of Thallium Sulphate by the Office of the National Security Adviser (ONSA),” the letter read in part.
“The correspondence further indicated that information concerning the purported procurement is reportedly available to the political opposition leadership. In this regard, I am directed to respectfully convey that ONSA has neither procured nor initiated any process for the purchase of such material, and has no intention of doing so.
“However, I am further directed to state that the allegation has been formally referred to the Department of State Services for a comprehensive investigation. Your Excellency and other parties involved, who may possess relevant information relating to this claim will be duly invited by the Service to provide any evidence that may assist in an in-depth investigation, establishing the facts and ensuring due diligence.
“Please accept the assurances of the esteemed regards of the National Security Adviser.”
TheCable gathered that an initial attempt to deliver the response letter to El-Rufai’s Abuja residence on Friday was unsuccessful, as security operatives reportedly declined to receive it, citing the absence of the head of security and uncertainty over when the former governor would be available.
The letter was eventually delivered on Sunday and received by the head of security on El-Rufai’s behalf.
El-Rufai had also alleged during an appearance on ARISE Television’s Prime Time programme on Friday that he accessed an intercepted telephone conversation involving the NSA, claiming that “someone tapped” Ribadu’s phone and that he listened to a conversation in which the NSA allegedly directed security operatives to arrest him.
The DSS is expected to investigate the claims as directed by ONSA.