The Office of the National Security Adviser (ONSA) has challenged former Kaduna State Governor, Nasir El-Rufai, to submit evidence supporting his allegation that the agency procured thallium sulphate, a highly toxic chemical compound, for investigation by the Department of State Services (DSS).

 

Thallium sulphate is widely regarded as a highly poisonous, colourless and odourless substance capable of causing death in small doses. El-Rufai had alleged that the compound was sourced from a supplier in Poland and accused the ONSA, under the leadership of Nuhu Ribadu, of procuring approximately 10 kilograms of the substance. He demanded urgent clarification over the alleged transaction.

 

In response, the ONSA firmly denied the claim and called on El-Rufai to provide any evidence in his possession to the DSS to enable a thorough and independent investigation.

 

According to reports by TheCable, a copy of the ONSA’s official response, addressed to El-Rufai’s Abuja residence, was initially rejected by security operatives on duty. The operatives reportedly informed the dispatch clerk that the head of security was not present and that they were unsure when the former governor would be available to receive the correspondence.

 

The letter was eventually delivered on Sunday, with the head of security signing to acknowledge receipt on El-Rufai’s behalf.

 

The response, dated February 13, 2026, was written by Brigadier-General O.M. Adesuyi on behalf of the National Security Adviser.

 

In the letter, Adesuyi stated that the ONSA had neither procured nor initiated any process for the purchase of thallium sulphate and had no intention of doing so. He added that the allegation had been formally referred to the DSS for comprehensive investigation.

 

The letter further indicated that El-Rufai and any other individuals in possession of relevant information would be invited by the DSS to provide evidence that could assist in establishing the facts and ensuring due diligence.

 

The ONSA concluded by reaffirming its commitment to transparency and due process in addressing the allegation.