The Office of the National Security Adviser (ONSA) has denied allegations that it procured the toxic substance thallium sulphate and has asked former Kaduna State Governor Nasir el-Rufai to submit any supporting evidence to the Department of State Services (DSS) for investigation.
The development follows a letter written by el-Rufai to the National Security Adviser, Nuhu Ribadu, dated January 30, 2026, in which he alleged that approximately 10 kilograms of thallium sulphate had been sourced from a supplier in Poland. Thallium sulphate is a highly toxic, colourless and odourless chemical compound capable of causing death even in small doses.
In its official response dated February 13, 2026, ONSA dismissed the allegation and referred the matter to the DSS for further scrutiny. The response, signed by Brigadier-General OM Adesuyi on behalf of the National Security Adviser, acknowledged receipt of el-Rufai’s correspondence and firmly denied any involvement in the alleged procurement.
Adesuyi wrote:
“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 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.”
Sources familiar with the development indicated that an earlier attempt to deliver the response letter to el-Rufai’s Abuja residence was unsuccessful, as security personnel reportedly declined receipt, citing the absence of the head of security and uncertainty about the former governor’s availability. The letter was later delivered on Sunday and received by the head of security on his behalf.
The controversy comes amid escalating tensions between el-Rufai and the national security establishment. During an appearance on Prime Time, an Arise Television programme, on Friday, el-Rufai claimed he had listened to an intercepted telephone conversation allegedly involving Ribadu.
According to him, “someone tapped” Ribadu’s phone and that he listened to the NSA allegedly directing security operatives to arrest him.
The matter has now been formally handed to the DSS, with ONSA stating that any individuals possessing relevant information would be invited to assist in establishing the facts.
Ademide Adebayo
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