David Blunkett has defended the government's use of laws which allow indefinite detention of terror suspects
The army took part in an anti-terrorist operation at Heathrow
He says powers in the Anti-terrorism, Crime and Security Act 2001 were necessary to protect the UK from suicide bombers and others extremists.
"You can't deter when the deterrent no longer exists," he said during a keynote speech in New Delhi, India.
But the home secretary said it was vital to balance anti-terror measures with the protection of civil liberties.
Speaking at the start of a six-day visit to the Indian sub-continent, Mr Blunkett argued that the threat of prosecution was not enough to deter modern terrorism.
The 2001 Act, introduced after the 11 September atrocities, includes measures relating to the detention of suspected international terrorists, inciting religious hatred or violence, weapons of mass destruction and terrorist finance and property.
It has been widely criticised by human rights groups, but Mr Blunkett argues that governments must have powers to prevent terror.
"I accepted by necessity we have to have prevention under a new category
which is to intervene before the act is committed, rather than do so by due
process after the act is committed when it's too late," he said.
"This is a whole different ball game to anything that we have ever known
Mr Blunkett, speaking at the British Council, said it was "nigh on impossible" to square the circle that meant individual human rights were curtailed in order protect democracy.
"We have to be able to protect ourselves by intervening with individuals who
have taken actions that put our lives at risk, disrupt our justice and our
democratic processes," he said.
In the UK 16 foreign nationals have been detained under the Act, after being certified as suspected international terrorists.
Mr Blunkett argued that there can be no negotiation with suicide bombers and international terrorists.
And he said that ultimately the best security comes through good intelligence.
During his visit, Mr Blunkett signed an agreement to speed up the deportation of Indian nationals who remain in the UK for too long,
Indian deputy prime minister Lal Krishna Advani has pledged to increase his government's
co-operation with Britain.
Under the deal, Indians who fail to win asylum in the UK and those who overstay on visas will
be issued with new travel documents within three months, compared with the
existing system which can take up to a year.
"The re-documentation and the ability to deal with this issue is indicative
of the tremendous strides we have taken together," said Mr Blunkett.