The Office of the National Security Adviser (ONSA) has challenged the former governor of Kaduna State, Nasir El-Rufai to provide evidence supporting his allegation that the agency procured a dangerous toxic substance, Thallium Sulphate into the country.

The former governor Nasir el-Rufai had alleged in a January 30, 2026 letter addressed to Nuhu Ribadu, the national security adviser, that ONSA obtained thallium sulphate — a highly toxic, colourless and odourless chemical capable of causing death even in small quantities, from a supplier in Poland.

But in a reply to Mallam El Rufai’s letter, the Office of the National Security Adviser while  denying that it neither procured nor initiated any process to acquire the chemical and had no intention of doing so, directed the former governor to forward any proof to the Department of State Services (DSS) for investigation.

The reply, dated February 13, 2026, and  signed by Brigadier-General O.M. Adesuyi on behalf of the NSA stated that the allegation had been formally referred to the DSS for a comprehensive probe and invited el-Rufai and any other individuals with relevant information to submit evidence to aid the investigation.

Mallam El-Rufai had claimed in a recent Television interview that he had listened to an intercepted phone conversation allegedly involving Ribadu, where trhe NSA directed that he should be arrested on arrival from abroad.