The Office of the National Security Adviser (ONSA) has asked Nasir el-Rufai, former governor of Kaduna State, to forward proof of his allegation regarding the procurement of thallium sulphate to the Department of State Services (DSS) for investigation.
Sources disclosed that the directive followed claims made by el-Rufai concerning the alleged acquisition of the substance. Thallium sulphate is known as a highly poisonous, colourless, and odourless chemical capable of causing death even in small quantities.
In a letter dated January 30, 2026, and addressed to the National Security Adviser, Nuhu Ribadu, el-Rufai alleged that the chemical was obtained from a supplier in Poland.
In response, ONSA denied the claim. The office also requested that any supporting materials in el-Rufai’s possession be submitted to the DSS for proper examination.
It was gathered that an earlier attempt to deliver the reply to el-Rufai’s Abuja residence was unsuccessful. Security personnel on duty reportedly declined to receive the document on Friday. They told the dispatch clerk that the head of security was absent and could not confirm when el-Rufai would be available.
The letter was eventually delivered on Sunday. The head of security later signed and acknowledged receipt on his behalf.
The correspondence, dated February 13, 2026, was written by Brigadier-General OM Adesuyi on behalf of the National Security Adviser.
It read: “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.”
Earlier on Friday, el-Rufai also claimed he had access to an intercepted telephone conversation involving Ribadu.
Speaking on Prime Time, a programme on Arise Television, he said “someone tapped” Ribadu’s phone and that he listened to the NSA allegedly instructing security operatives to arrest him.
