New Delhi, Jan 26 (IANS): Days of intense preparations and watchfulness paid off for over 50,000 security personnel deployed across the capital to ensure smooth celebrations of the Republic Day Sunday.

The parade along Rajpath was watched by thousands, including President Pranab Mukherjee, Prime Minister Manmohan Singh and Japanese Prime Minister Shinzo Abe, who was the chief guest.

"We were preparing for a safe and secure Republic Day celebration for the past week. Now we are feeling relaxed that it went off smoothly," a top police official told IANS.

Over 35,000 Delhi Armed Police personnel and over 5,000 from paramilitary forces were deployed along the Republic Day Parade route - from the sprawling Vijay Chowk at the foot of Raisina Hill to the historic Red Fort seven km away.

A vast ground-to-air security apparatus was put in place in the city Sunday and snipers with sophisticated arms and binoculars were perched on rooftops along the way.

Mobile quick response teams, anti-aircraft guns and sharpshooters of the elite National Security Guards (NSG) with around 500 men of the Central Industrial Security Forces (CISF), 15 companies or 1,500 men of the Central Reserve Police Force (CRPF) were also on the job at various spots on the route and near key infrastructure points.

"Some 125 buildings around the Rajpath were sealed and rooftop surveillance mounted to keep subversive activities at bay," Joint Commissioner of Police (New Delhi) Mukesh Kumar Meena said earlier.

Other parts of the city were also placed under a tight security net, with police barricades and check posts on many routes, including the state border areas.

Unmanned Aerial Vehicles (UAV) were also deployed for surveillance from 5 a.m. to 12.30 p.m. Sunday to secure the air as Indian Air Force fighter planes put up a spectacular flypast.

After the parade, the air space over the capital, that was shut for an hour from 11.15 a.m. to 12.15 p.m., was opened for regular commercial flights and air force operations.

Rajpath, which was closed for all vehicle movement from 6 p.m. Jan 25, was reopened.

Movement on Tilak Marg, Bahadurshah Zafar Marg and Netaji Subhash Marg up to the Red Fort that was restricted from 4 a.m. Sunday was also restored to general public after the march past.

Delhi Metro had closed down its station parking from 2 p.m. on Jan 25 till 2 p.m. on Sunday.