Delhi police on Monday took control at all Games venues, and about 175,000 paramilitary have been deployed to guard the city from terrorist strikes.
Australians have been warned the October 3-14 Games will occur in an environment of a high risk of terror attacks.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Some 80,000 Delhi police on Monday assumed management of security at Games venues in the Indian capital, parts of which remain flooded due to persistent monsoon rains.
An organising committee source said on Monday up to 1500 police would be manned at each sporting stadium for the Games, while elite commando units have been summoned to protect VIPs.
The commandos include specialist bomb disposal units on heightened alert.
Unheralded measures will also be enacted for the opening and closing ceremonies of the Games.
The source said an air space shutdown would be enforced for five hours either side of the Games ceremonies.
The only aircraft allowed into the air space around the main arena, the Jawaharlal Nehru Stadium, would be helicopters manned by defence and security specialists.
Organising committee officials would not comment on the massive security measures, which the source said included placement of commandos on each floor of every building in the athletes village.
A police station would also be opened inside the village to cater only for athletes and officials, the source said.
The village is to officially open on Thursday as athletes and officials from 71 commonwealth nations begin arriving for the Games.
Officers from the crack National Security Guard had been stationed around the city, and on Monday were visible outside the organising committee headquarters in central New Delhi.
The guards, armed with rifles, replaced the more common Delhi police who were stationed outside the building which also houses the Commonwealth Games Federation.
Monsoon rains continue to disrupt preparations for the Games, with much infrastructure remaining incomplete within three weeks of the opening ceremony.
New Delhi is braced for rising flood levels of the Yamuna River which bisects the city and surged four metres in height on Sunday.
The river level is expected to remain above danger levels this week as construction crews battle the wet weather to get final work completed on the 17 sporting venues.
But the Games' organising committee chairman Suresh Kalmadi remained hopeful the weather would improve.
"Nature has been a little problem ... there have been many challenges and we face up to many challenges and things will work out very fine," Kalmadi said.
