Azimio leader Raila was on Tuesday asked to leave the entrance to the Directorate of Criminal Investigations headquarters as supporters continued to mill around.
Tens of Azimio supporters have gathered around Mazingira House, Kiambu Road.
The opposition leader had been driven to the DCI head offices where former Interior Cabinet Secretary Fred Matiang'i is recording a statement.
Moments after Raila arrived, Head of Police Operations at the DCI Said Kiprotich and Head of Investigations Eliud Lagat stepped out to speak to Raila at the entrance.
They told Raila that his presence at the DCI headquarters was unwelcome as it was creating unnecessary tension.
"I am under instruction that none of you should be allowed to come in," a police officer told Raila, in a heated argument at the gate.
Matiang'i is currently at the DCI head offices where he is recording a statement in connection to an alleged raid at his Karen home last month.
Raila furiously told off the police officers who barred him from accessing the DCI headquarters.
"I am a public officer, I cannot be barred from a public office, I have to see the director, what law is that," Raila charged.
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