Human rights laws must be re-written to protect the public against terrorism, Home Secretary John Reid said in Venice.
In a controversial speech, he described the current legal set-up as "unacceptable" and said politicians who followed case law "to the letter" were failing to protect their citizens. He insisted the international legal landscape required modernising, while still safeguarding human rights.
Speaking at a conference of interior and home affairs ministers from the six largest European Union countries, Mr Reid said legislation which distinguishes between armed conflict and criminal acts was effectively out of date.
"We need to work to modernise the law - still protecting human rights and still providing equity and justice - but reflecting the reality of the conflicts and struggles we now face," he told the G6 summit.
"We need leadership to do this. It can't be left solely to the lawyers. Politicians must expose these issues and set a lead, so that we can protect the rights of all our citizens, including all those threatened by terrorism."
Referring to the post-September 11 scenario of global al Qaida-inspired terrorism, he said: "We are all having difficulty adapting to this new situation for which neither the law of war, as previously defined, nor the normal civil law is particularly designed or well suited.
"Unless we address this gap we are likely to be pushed in two competing directions.
"Either to look for ways round the law in order to safeguard the security of our citizens - a way that takes us towards options like Guantanamo or the row all of us in the EU saw recently on rendition.
"Or instead to follow the law, including case law, to the letter and thereby fail in our primary duty as elected politicians to protect the public through, for example, our inability to deport terrorist suspects.
"Neither is acceptable nor is either the right response to the threat."