The incident occurred near Kadakkal about 50 km from the state's capital.
Local legislator Mulakara Ratnakaran told the media that after hearing about the incident, he spoke to the top police officials in Kollam district.
"An officer told me that the policeman who did this has been suspended and a probe has been initiated. What happened is most unfortunate," said Ratnakaran.
The incident occurred when the youth driving a bike was asked to stop by policemen who were checking vehicles. When he did not stop policeman Chandramohan hurled his lathi which hit the youth's head and he lost control following which his bike crashed into a car leaving him seriously injured.
The police officials stopped the checking after angry onlookers reacted to the incident.
The injured youth was rushed to a nearby hospital where he was diagnosed with a serious head injury. He was then taken to the state run Medical College hospital here.
Kollam District Superintendent of Police (Rural) Harisankar after hearing about the incident immediately suspended Chandramohan and ordered a probe into the incident.
Incidentally, the Kerala High Court has come down heavily on the manner in which police officials resort to checking vehicles on busy roads. It has asked them to do it only where the roads are straight and not winding.
( With inputs from IANS )