Nigeria, Feb. 15 -- Former Kaduna State Governor Nasir El-Rufai has written to the National Security Adviser, Nuhu Ribadu, requesting clarification over reports that the Office of the NSA imported about 10kg of thallium sulphate, a highly toxic substance, from Poland. In the letter, El-Rufai asked for details on the purpose, supplier, quantity, storage, regulatory approvals, and public-health safeguards, including oversight by NAFDAC and NCDC. The request follows El-Rufai's recent claims during an interview on ARISE Television that Ribadu ordered an attempt to arrest him at Nnamdi Azikiwe International Airport, Abuja, alleging his phone was tapped. Ribadu has not publicly responded. El-Rufai, who says he is being politically targeted, als...