Police believe the horns were destined for the neighbouring Tanzania but it was not immediately clear where they were sourced from.
The officer is attached to the Industrial Area Police Station in Nairobi and is believed to be part of a poaching cartel in the country, mainly offering security.
“They were stopped by the Kenya Wildlife Service (KWS) officers and police officers who had been tipped off about the transportation of the prized horns,” a police officer told Capital FM News on Tuesday, soon after the arrests.
He said the officer had threatened to open fire when they were stopped, but was eventually subdued and hand-cuffed.
The suspects were expected in court later Tuesday afternoon.