The Office of the National Security Adviser (ONSA) has challenged former Kaduna State Governor, Nasir El-Rufai, to submit any evidence backing his claim that the agency procured thallium sulphate, a highly toxic chemical compound.
Thallium sulphate is a colourless and odourless substance capable of causing death in small doses. El-Rufai had alleged that about 10 kilograms of the compound were sourced from a supplier in Poland and demanded clarification from the National Security Adviser, Nuhu Ribadu.
In a formal response dated February 13, 2026, and signed by Brigadier-General O.M. Adesuyi on behalf of the NSA, ONSA denied the allegation and said the matter had been referred to the Department of State Services (DSS) for investigation.
“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.
“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.”
Letter Delivery Drama
According to TheCable, an initial attempt to deliver the response to El-Rufai’s Abuja address was unsuccessful after security operatives on duty reportedly declined to receive the correspondence, citing the absence of their head of security and uncertainty about the former governor’s presence.
The letter was eventually delivered on Sunday, with the head of security signing and acknowledging receipt on El-Rufai’s behalf.
The latest exchange deepens the dispute between El-Rufai and the Office of the National Security Adviser, with the former governor insisting on transparency over the alleged chemical procurement and ONSA firmly rejecting the claim while inviting formal evidence for investigation.
