The Office of the national security adviser (ONSA) has asked former Kaduna State governor, Nasir El-Rufai, and other Nigerians to submit evidence of the alleged procurement of Thallium Sulphate to the Department of State Services (DSS) for further investigation.
Thallium sulphate is a highly toxic, colourless and odourless compound that can kill humans in small doses.
According to TheCable this allegation is contained in a letter dated January 30, 2026, and addressed to Nuhu Ribadu, the National Security Adviser, by El-Rufai who alleged that the substance was sourced from a supplier in Poland.
ONSA replied him denying the allegation and asking him to supply any evidence he has to the DSS for a thorough investigation.
However, the publication stated that that a copy of the response sent to El-Rufai’s Abuja address was rejected by the security operatives on duty on Friday.
They reportedly told the dispatch clerk that the head security was not on the ground and that they did not have an idea of when el-Rufai would visit.
But it was eventually delivered on Sunday and the head of security signed and received it on behalf of el-Rufai.
The response, written by OM Adesuyi, a brigadier-general, on behalf of the NSA, and seen by TheCable, was dated February 13, 2026.
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.”
On Friday, el-Rufai had also said he accessed an intercepted telephone conversation involving Ribadu.
Speaking on Prime Time, an Arise Television programme, he said “someone tapped” Ribadu’s phone and that he listened to the NSA allegedly directing security operatives to arrest him.
