Mombasa police on Friday morning arrested Airport Ward Rep Ibrahim Omondi.
About 15 police officers raided his Changamwe home at 5am, Josephine Ibrahim, his wife said.
Coast police boss Larry Kieng confirmed the MCA is in their custody saying, “we are investigating him concerning a very serious offence on national security”.
On Thursday several Mombasa MCAs warned the electoral commission against conducting an election in the county on October 26.
The ward representatives allied to Nasa declared there will be no election in the county.
Mrs Ibrahim said the MCA’s arrest could be linked to a statement he made during the event.
A video went viral on social media showing Mr Omondi dismissing President Uhuru Kenyatta as a caretaker and not the president.
“Uhuru Kenyatta should be very careful. He is not even the President of Kenya, he is a caretaker president and he is supposed to respect the constitution just like any other citizen of this country,” the MCA allegedly said in the video.