A series of airspace restrictions¹ around London and south-east England are set to be enforced as part of security for the 2012 Olympic Games.

为加强2012年奥运会的安全，伦敦周围以及英格兰东南部地区开始了一系列的航空管理。

The Ministry² of Defence said equipment and personnel from the Royal Navy, Army and Royal Air Force will be in place from Saturday to secure the area.

It comes as it emerged that 3,500 extra service personnel would be needed to bolster³（支持） security at the Olympics.

Defence Secretary Philip Hammond said the Games will be "safe and secure".

The temporary additional restrictions to airspace in and around the capital comes into force at 00:01 BST on Saturday (23:01 GMT on Friday) and will last for a month.

The prohibited zone will be about 30 miles wide and does not affect commercial aircraft, which fly in established air traffic corridors.

As part of Friday's build-up to the airspace restrictions, Sea King helicopters are being deployed⁴ to RAF Northolt.

And HMS Ocean is set to return to London with a deployment⁵ of Royal Marines to provide security on the River Thames.

It comes the day after ground-based air defence systems were installed at four sites in and around London.

Earlier this week, Typhoon fighters were deployed to RAF Northolt, while RAF Puma⁶ helicopters and snipers were deployed to Ilford in east London.

The Ministry of Defence (MoD) said they would all support the air security plan when the extra airspace restrictions over London come into force.

Meanwhile, the Civil Aviation Authority (CAA), National Air Traffic Services (Nats) and the MoD have worked together to inform airspace users about the restrictions and how people can continue to use the UK's airspace during the Olympics.

Pilots have a legal requirement to understand airspace changes before each flight and the CAA has written to all private pilots, distributed more than 60,000 leaflets（传单） and conducted briefings to raise awareness⁷ of the restrictions.

BBC defence correspondent Jonathan Beale said if a private plane did enter the restricted zone, a graduated response would be triggered, beginning with a warning and potentially ending in the aircraft being shot down.