The Office of the National Security Adviser, ONSA, has dared former Governor of Kaduna State, Nasir El-Rufai, to submit evidence of the alleged procurement of thallium sulphate to the Department of State Services, DSS, for further investigation.

The thallium sulphate is a highly toxic, colorless, and odorless compound that can kill humans in small doses.

El-Rufai had said the substance was reportedly sourced from a supplier in Poland.

Recall that El-Rufai had accused the ONSA, under Nuhu Ribadu of procuring thallium sulphate, a highly toxic chemical compound, and has demanded urgent clarification over the alleged transaction.

Responding, the ONSA denied the allegation, asking El-Rufai to supply any evidence he has to the DSS for a thorough investigation.

According to TheCable, a copy of the response sent to El-Rufai’s Abuja address was rejected by the security operatives on duty.

The security operatives 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.

Meanwhile, it was eventually delivered on Sunday and the head of security signed and received it on behalf of el-Rufai.

The response, written by Brigadier-General, OM Adesuyi, on behalf of the NSA was reportedly 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.”