Nakuru Town West MP Samuel Arama spent the night in custody after he was arrested on Friday night by EACC officers over suspected land fraud.
He is being held at Nakuru Railways Police Station.
His brother Charles Arama said the MP was arrested at 9.30pm alongside his lawyer.
Family members, friends and his supporters have been streaming into the Railways Police station to plead for their release.
EACC officers hinted that they may be looking for more suspects and full information will be availed to the public later.