New Delhi: The airspace over the Indian capital will be closed for a few hours in the morning and anti-aircraft guns trained skywards to target any unknown airborne object as part of tight security for Republic Day celebrations Friday.

There will be over a dozen fighter aircraft poised to take off from Palam and other nearby air bases in case of any eventuality.

Nearly as many anti-aircraft guns will be installed at undisclosed locations all over India Gate and Rajpath, the main venue of the national parade.

Over 26,000 security personnel will man the 12-km route from Vijay Chowk to the 17th-century Red Fort for the parade that showcases India's military might, economic prowess and cultural diversity.

Security personnel, including from Delhi Police and the military, are leaving nothing to chance.

While the Indian Air Force (IAF) will revise its 'standard operation procedure' to ensure an airspace security canopy, police will erect an impregnable security shield at India Gate, a World War I monument and a symbol of Delhi, as well as the entire stretch of the parade route till the Mughal-built Red Fort.

The police, in fact, are taking extra pains to ensure that no untoward incident occurs at any public place in the city.

Apart from Delhi Police, various paramilitary forces, including the elite National Security Guards, will be deployed along the parade route, said Ranjan Bhagat, the Delhi Police spokesperson and assistant commissioner of police.

With important dignitaries like President A.P.J. Abdul Kalam, the supreme commander of the armed forces, Russian President Vladimir Putin, the chief guest at the parade, Prime Minister Manmohan Singh and several other VIPs watching the celebrations, the maximum concentration of security personnel will be close to India Gate.

In an indication of the attention that police is paying to security arrangements at Rajpath, the short distance of four kilometres from Vijay Chowk to Tilak Marg has been divided into 12 sectors, with each sector of less than 300 meters placed under the control of a deputy commissioner of police.

With reports that some militants have sneaked into the capital to target Congress President Sonia Gandhi, security and intelligence agencies are taking no chances. They have been extra cautious for the past few days, enforcing strict security measures on the ground.

The security arrangements have been reviewed several times at meetings of the home and defence ministries as well as intelligence agencies.

In the wake of reports that jehadi groups might try to hijack an Indian plane to force the release of parliament terror attack convict Mohammad Afzal Guru, the Bureau of Civil Aviation Security (BCAS) has directed the Central Industrial Security Force to remain on high alert at airports across India, particularly in New Delhi and Mumbai.

 The army has carried out mine proofing of the Vijay Chowk lawns before handing it over to Delhi Police, which have pressed their sniffer dog squad to sniff out possible hidden explosives.

Besides erecting barricades along the parade route, policemen will be deployed on rooftops to keep a birds' eye view.