The Senate has invited the heads of security agencies appearing before it into the chamber.
President of the Senate, Bukola Saraki, said the security briefing would be held behind closed doors.
Journalists, aides and guests in the chamber have been sent out. The doors were closed at 12:30pm.
The Director-General of the Department of State Services, Lawal Daura; and the Chief of Defence Staff, General Abayomi Olonisakin, had arrived at the Senate to address the lawmakers on the security situation in the country.
While Olonisakin arrived earlier, Daura arrived around 11:25am.
Both of them waited at the office of the Special Assistant to the President on National Assembly Matters (Senate), Senator Ita Enang, to be called into the Senate chamber for the address.
The Senate had sumoned the service chiefs and heads of security agencies in the country, including the Nigerian Immigration Service and the Nigeria Customs Service, to address the lawmakers.
It was, however, learnt that apart from Daura and Olonisakin, other heads of security agencies sent their representatives.