By Ayanjit Sen
BBC News, Delhi
Heavy security arrangements have been made by the Indian authorities for Republic Day on Wednesday.
The authorities want to ensure the celebrations are not disrupted
More than 25,000 security personnel will be deployed in Delhi to protect senior politicians and other VIPs.
The Republic Day parade features colourful marches by contingents from the army, navy, air force, paramilitary and police organisations.
The parade will be part of celebrations to mark the 56th anniversary of India's foundation as a republic.
In Delhi, extra policemen has been deployed at airports, railway stations, embassies and tourist spots.
Nearly 600 commandos from the elite National Security Guard and the Indo-Tibetan Border Police have been deployed in the capital.
The authorities say that there will also be security personnel posted on high-rise buildings, and bunkers have been set up along the parade route.
A senior police official said extensive plans have been made to counter "any eventuality".
The Bhutanese king will be the guest of honour
The function in Delhi is expected to be attended by the Prime Minister Manmohan Singh, the President, APJ Abdul Kalam and other senior leaders and foreign dignitaries.
Heavy security arrangements are also being made in the cities of Mumbai (Bombay), Calcutta and Madras (Chennai) for Wednesday's celebrations.
Security has been beefed up in Indian-administered Kashmir, particularly in Srinagar and Jammu, where official functions are scheduled to be held.
In the past, militants have tried to disrupt official functions on the occasion by carrying out blasts or firing rockets.
Separatist groups have declared Republic Day a "Black Day", and have asked people to close their businesses.
Meanwhile, a leading student group in India's north-eastern state of Arunachal Pradesh has said it will join the separatist rebel groups of the region in boycotting Republic Day celebrations.
The All Arunachal Pradesh Students Union said the central government has not done anything to deport around 60,000 Chakma and Hajong people who they say unlawfully came to the state from what was then East Pakistan.
The students union is demanding that the Chakmas and Hajongs should be ejected from the state because they are unwelcome foreigners.
Six other separatist groups in north-east India have called for a boycott of Indian Republic Day celebrations to protest against what they describe as India's colonial control of the region.
Security arrangements throughout the area has been beefed up, particularly in the state of Assam, where rebels have set off at least seven explosions recently.