Home Minister P Chidambaram today hit out at CPI(M) for seeking to link Trinamool Congress leader Mamata Banerjee to Rajdhani Express hijack and talked tough on Maoist violence, saying no democracy can accept "violence as an instrument of change".

"CPI(M) seems to know more about what is happening in Trinamool Congress than what is happening in West Bengal. I think these are baseless charges," Chidambaram told reporters when referred to CPI(M) leader Prakash Karat's charge that Banerjee was linked to the hijacking.

"Just because CPI(M) and Trinamool are opposed in West Bengal, responsible political leaders should not hurl charges against other equally responsible leader," he said, adding, "I am not at all happy that such charges should be levelled against a political leader."

Karat had yesterday suggested that People's Committee against Police Atrocities (PCPA), which detained the train carrying about 1,200 passengers, had political patronage of Mamata Banerjee, the Railway Minister.

Chidambaram said there was no intelligence input to suggest that the train would be detained in West Bengal on Tuesday and a probe is being conducted to ascertain who was behind the act.

He said if anyone in the government knew that Rajdhani Express would be detained, it would have made an attempt to nip it in the bud.

On the government's approach to deal with naxalism, the Home Minister said, "I have already stated our position. We do not accept violence and our security forces will act against anybody or group which engages in violence."

"The only thing I have been saying is abjure violence, we are willing to talk," he said.

"As long as they don't abjure violence, is it not the duty of the state -- central government and state government -- to take action against those indulging in violence?... Violence is unacceptable, violence must stop," he emphasised.

Describing the Rajdhani Express episode as a wake-up call, Chidambaram said violence hitherto used to take place in remote places but when it happened with Rajdhani train, people woke up.

"Today, violence is against a police officer, it can be against 1,200 passengers in a train....I have been giving this wake-up call for several months," he said.

Disagreeing with the contention by some quarters that the government was at "war" with the naxals, he said this word is used only by CPI(M) and the media. "No civilised society will go to war against its own people but people will have to stop violence."

On Karat's contention that the centre was not ready for a joint operation against the Maoists in West Bengal, Chidambaram said the CPI(M) leader "should talk to his Chief Minister, he will tell him the actual situation."

The Home Minister said "maximum forces" have been given to West Bengal for three districts where militants are operating.

"The Chief Minister is fully aware of all the action that has been taken. I have briefed the Chief Minister personally," he said.

While talking about the ways to deal with naxalism, Chidambaram referred to an effort by Digvijay Singh as Chief Minister of Madhya Pradesh while dealing with a violent group in Balaghat.

Singh had proposed to reduce police presence if there was no violence for three months.

Chidambaram, however, said it did not mean that that particular example would work everywhere.