When water cannon and teargas failed to disperse the Congress demonstrators near the Lower PMG close to the Assembly building the police used batons, police sources said.
The demonstrators retaliated with stones, they said.
Among the injured were DCP Nitinjeet Singh and seven policemen, the sources said.
A dozen demonstrators were also injured in the police action, the sources said.
Earlier, the demonstrators were addressed by Congress stalwarts including state in-charge Jagdish Tytler and PCC President Niranjan Patnaik who dubbed the the BJD government as the most corrupt in Odisha.
The Congress leaders also raised the coal block allocation and fertiliser scarcity issues and held the chief minister responsible for irregularities.
Accusing the state government of depriving the poor of rice and wheat provided by the Centre, the Congress leaders alleged that the BJD government was providing only 25 kg per family against 35 kg given by the central government under various schemes like Antyodaya Anna Yojana.
Denying the allegations, the chief minister told reporters that the charges against the BJD were meaningless in view of the scams in which the Congress-led UPA government was allegedly involved.