John Reid, the Defence Secretary, has called for a sweeping overhaul of international law to counter the threat of terrorism.
Acknowledging the idea would be "controversial", Mr Reid declared yesterday that radical changes were necessary to the Geneva Convention, that there should be a right to carry out pre-emptive strikes on a perceived threat and that intervention should be allowed in another sovereign country to save its people from internal repression.
He maintained that the alterations were necessary to counter terrorist organisations which were capable of carrying out devastating attacks while ignoring laws which governments have to abide by.
Critics claimed, however, that such "reforms" would herald a slide towards draconian actions by the Government, such as practised by the Bush administration at Guantanamo Bay, hitherto held to be illegal by British courts.
It would also have provided another excuse for invading Iraq in the light of the Government's failure to prove that Saddam Hussein was producing weapons of mass destruction.
More immediately the changes would allow military strikes against installations in Iran, suspected of attempting to manufacture nuclear weapons, which government ministers privately say will breach current international laws.
Mr Reid said "We risk trying to fight a 21st century conflict with 20th century rules which, when they were devised, did not contemplate the type of enemy which is now extant.
"The laws of the 20th century placed constraints on us all which enhanced peace and protected liberty. We must ask ourselves whether, as the new century begins, they will do the same. We now have to cope with a deliberate regression towards barbaric terrorism by our opponents. The legal constraints upon us have to be set against an enemy that adheres to no constraints whatsoever."
On the question of confronting regimes brutalising their own people, Mr Reid received an element of support from shadow Foreign Secretary William Hague. Mr Hague, on a visit to Darfur, said the international community must do more to provide "protection and security" for the people of the Sudanese province.