Nakuru Town West MP Samuel Arama spent the night at Nakuru Railways Police Station after anti-graft detectives arrested him over suspected land fraud.
His brother, Charles, told Nation the MP was arrested at a bar in Nakuru town at about 9pm on Friday.
The brother said he was arrested "because of a land dispute."
Several Jubilee Party leaders, after learning of his arrest, are now seeking to mobilise Mr Arama’s supporters to head to the Railways Police Station where he is being held to push for his release.
Nakuru County Jubilee secretary-general, Mr Peter Cheruiyot, said police have not given reasons for Mr Arama’s arrest and are "holding him in a station full of mosquitoes."
Security has been beefed up at Railways Police Station after Mr Arama's supporters camped at the outside the station's gate demanding his release.
Nakuru OCPD Samuel Obara is at the scene.
"EACC [Ethics and Anti-Corruption Commission] investigating officer says he is waiting for orders from the DPP [Director of Public Prosecutions]. We fail to understand how the two agencies link which has made us feel there is more to this matter," said Nakuru East MP David Gikaria, who was one of the first legislators to arrive at the police station.