Modi provided adequate security: Chidambaram on BJP's claim

"Adequate security has been provided to Modi, the state governments have been asked to provide full proof security. He has addressed 400 rallies across the country. No one can point a finger on security provided," he said.

This comes after a woman passenger was killed and 14 others were injured when two blasts occurred in an express train at the Chennai Central Railway Station on Thursday morning.

BJP spokesperson Nirmala Sitharaman said threat perception was there and they had informed Shinde.

She said it happened close to the party's prime ministerial candidate Narendra Modi's campaign trail.

BJP expresses its note of caution at this moment, she said.

According to reports, the blasts occurred around 7.30 am in the sleeper coaches S4 and S5 of  Train No.12509, Bangalore-Guwahati Express as it entered platform number 9 of the station. Both coaches were damaged in the blasts.

The woman who lost her life in the incident was identified as Swati, 24. She was an employee of the Tata Consultancy Services (TCS).

The Railways announced a compensation of Rs 1 lakh to the family of the woman killed in the blasts.

Of the 14 injured, condition of two are serious and they are being operated upon, said the Railways.

All injured were admitted to Rajiv Gandhi Government General Hospital.

"There were two separate low intensity blasts inside the train. The police are investigating the matter," said Southern Railways General Manager Rakesh Mishra.

According to reports, the Tamil Nadu Police said the twin blasts were an act of terrorism.

The National Investigation Agency (NIA) has  sent two teams to assist the Tamil Nadu Police in its investigations. 

A Special Investigation Team (SIT) has also been constituted to probe the blasts.

Prime Minister Manmohan Singh in Chennai said: "The act highlights the desperation and cowardice of those responsible."

Railway Minister Mallikarjun Kharge said they are taking quick action and will soon reach a conclusion on the incident.

A senior railway police official in Bangalore said: "We have upgraded security by posting armed guards, task force. In Bangalore we have three for railways stations."

Tamil Nadu Chief Minister J Jayalalithaa on Thursday ordered Crime Branch-Crime Investigation Department (CB-CID) probe into the incident.

Meanwhile, Union Home Minister Sushilkumar Shinde has offered all forms of assistance to the state government.

"I am in Himachal Pradesh at the moment. But I have directed my officials to provide all sorts of assistance to the state government," Shinde told media over phone.

The police on Thursday released one of the two suspects detained in the twin blasts at the Chennai Central Railway Station.

The railway police had detained a man who was found hiding in the train with explosives. But he was later released as he was found "innocent" by the cops.