Police on Tuesday sealed off Jacaranda grounds where the National Super Alliance had planned to hold a memorial service for 27 supporters killed during election protests, even as President Uhuru Kenyatta is sworn in for a second term at Kasarani stadium.
City mortuary has also been sealed off by police and families of deceased denied access.
Police in full anti-riot gear threw teargas everywhere including residential estates as NASA supporters blocked road.
Raila had dismissed plans to have a parallel swearing-in ceremony saying it would only lead to anarchy and probably lead to more deaths.
He cited Ivory Coast and Gambia which had been faced by a similar election crisis culminating in the parallel swearing-in of Alassane Quatara and Adama Barrow respectively, saying their situation was not the same as Kenya.