A protest march by the Opposition Congress towards the Kerala DGP office here on Saturday turned violent with agitators hurling stones and sticks at the police following which water cannons were used to disperse the crowd.

The march was organised by the Kerala Pradesh Congress Committee (KPCC) alleging police atrocities against its workers during their agitation over the ongoing 'Nava Kerala Sadas' outreach programme of the Left government.

Senior leaders including KPCC chief K Sudhakaran, Leader of Opposition in the assembly V D Satheesan, senior leader Ramesh Chennithala, Thiruvananthapuram MP Shashi Tharoor and others were present on the makeshift stage near the DGP office when the police used tear gas and water cannons.

Sudhakaran and Chennithala were visibly affected by the tear gas used by the police and were escorted by the Congress workers to an available car nearby.

Both the leaders have been taken to a nearby hospital for necessary treatment.

Speaking to media from the hospital, Sudhakaran termed the attack against the party leaders as 'unprecedented'.

"We were holding a peaceful protest. The goons among the police attacked without any provocation while senior leaders were present," he claimed.

Hitting out at the police, Satheesan said such an "attack" against the leaders took place for the first time in the history of Kerala.

"The police acted upon the directions of the Chief Minister to harm the Congress leaders. Th police chief has handed the reins of Kerala's security to the ruling CPI(M). Certain people in the CMO are controlling the police force," Satheesan alleged in a statement.

Thiruvananthapuram MP and senior Congress leader Shashi Tharoor said a tear gas shell burst just behind the stage where at least six MPs and numerous party MLAs were present.

Tharoor said it was a "premeditated" attack on the Congress party.

"We want to know upon whose instruction the party leaders were attacked. We have the right to protest in this country. The MPs and MLAs will approach the respective privilege committees against this attack on elected representatives," he said. Meanwhile, Chennithala said the police attacked without any provocation and the leaders complained of breathlessness.

As soon as Sudhakaran concluded his speech, the party men started climbing the barricades erected near the DGP office and attempted to force their way past the security cordon.

As Satheesan was addressing the workers, a tear gas shell exploded behind the stage following which the meeting ended abruptly.

Later, the police used water cannons and fired tear gas shells forcing the workers and the leaders to disperse.

Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.