Surface-to-air missile defence systems will be deployed at six sites in London during the Olympics as a "powerful deterrent" against attack, Britain's Ministry of Defence confirmed Tuesday.

The news came despite angry protests from residents at two locations where missiles are being deployed on top of blocks of flats. One residents' group is taking legal action to try and stop the missile deployment.

Other steps being taken to protect the Olympics include mooring a helicopter carrier in the River Thames and stationing RAF Typhoon jets and Puma helicopters on the outskirts of London.

The ministry announced plans last year to deploy high-speed missile systems to protect the Olympic Park from aerial threats, as part of a mammoth security operation for the Games.

It placed the unarmed equipment at six sites in east London for nine days in May during a military exercise to test its air security plan.

Rapier and high velocity missile systems will be installed at those locations from mid-July and will remain there throughout the Games, the ministry said in a statement confirming the plans.

"Collectively, the systems include a range of air defence capabilities, including radar and detection equipment as well as weapons which will provide a powerful deterrent and protection against the threat of an attack from the air," the statement said.

It added that similar systems had been deployed at all recent Olympic Games.

Britain's biggest-ever peacetime security force of more than 40,000, backed by a huge intelligence operation, will also guard venues, athletes and the millions of visitors expected to throng the British capital.

Defence Secretary Philip Hammond said: "Whilst there is no reported threat to the London Olympics, the public expects that we put in place a range of measures aimed at ensuring the safety and security of this once-in-a-generation event.

"Ground-based air defence systems will form just one part of a comprehensive, multi-layered air security plan which, I believe, will provide both reassurance and a powerful deterrent."

Tenants living near the Olympic Park in Stratford, east London, launched legal action last week over proposals to station missile systems on the roof of their block of 100 local-authority owned flats.

Lawyers for residents of the Fred Wigg Tower in Leytonstone lodged papers at the Royal Courts of Justice, seeking an injunction to stop the systems being based there, claiming the plans breached tenants' human rights.

Hammond said the MoD "will defend these proceedings vigorously and is confident of defeating them."

The MoD has said the missiles would only be used in the event of "specific orders from the highest levels of government in response to a confirmed and extreme security threat."