The city will be on “general alert” on Republic Day, home secretary Ardhendu Sen said at Writers’ Buildings on Monday.

Railway stations, the airport, hotels and malls will be under special surveillance. More than 5,000 additional personnel will be deployed and closed-circuit television cameras installed at 60 points in Calcutta, added the home secretary.

“There is no specific threat but we are maintaining vigil at every vital point,” said Sen.

He, along with chief secretary Asok Mohan Chakrabarti and police commissioner Gautam Mohan Chakrabarti, surveyed the security arrangements for the parade on Red Road during the day.

“Police and the administration are trying their best to minimise risk factors. I request people to cooperate with the security personnel to avert any untoward incident,” said the chief secretary.

Senior police officers examined the seven watchtowers around Red Road from where armed cops will keep an eye on the area.

Sniffer dogs checked the stretch and the adjoining grounds for explosives planted in the ground.