Interior Cabinet Secretary Fred Matiang'i has ordered for thorough investigations to be carried out after a man slapped a woman said to be an election observer during the Ruguru Ward by-election in Nyeri County.

Share news tips with us here at Hivisasa

Matiang'i who spoke in Mombasa on Friday said the man who law enforcement agencies should have held as investigations into the incident continue was freed shortly after being arrested.

Matiang'i has now ordered Inspector General of Police Joseph Boinnet to ensure the senior police officer who freed the man who assaulted the woman be punished.

"Those people went to the police station and walked out just as they had walked in," Matiang'i told reporters in Mombasa.

"Police are hampering the process of justice. The police officer who freed that man should be disciplined... in fact be interdicted," he added.

Mathira West police boss Kiptoo Birgen confirmed the incident.

The man who slapped the poll observer claimed the assaulted lady, Martha Miano, was an election observer yet she had been seen campaigning for one of the candidates ahead of the ward election.

Mathira MP Righathi Gachagua had earlier questioned an IEBC official on the criteria the electoral agency used in issuing budges to election observers.

In a video widely circulated on social media, the MP is heard threatening to eject all 'campaigners' from the polling station.