According to police, the aspirants were protesting against the UPSC exam pattern.
Despite assurance given by a Congress leader that they could meet Union Minister V Narayanasamy on Tuesday and put forth their demands, they did not budge, police said.
They did not disperse from the place and were creating law and order problem, around 40 people have been detained as preventive measure, police said.
Aspirants were demanding relaxation in age and no restriction on the number of attempts for appearing in civil services examination.