About 50 policemen in 10 trucks have surrounded the premises of the Committee for the Defence of Human Rights in Adeniyi Jones area of Ikeja.
A protest demanding the release of Omoyele Sowore had been scheduled to take place at the venue at 10am today.
Sowore, candidate of the African Action Congress in the last presidential election, has been detained since August by the Department of State Services (DSS) who accused him of threatening public peace with the #RevolutionNow protest.
Eye witness say the security operatives have been at the premises since 7am.
When contacted, Bala Elkana, the Lagos police command spokesperson, said he was not aware of the deployment.