Proposals to allow police to stop and question anyone in the UK under new anti-terror laws have been criticised.
Police officers would be able to stop and question people
Opponents warned that plans to ask people about their identity and movements may harm community relations.
Northern Ireland Secretary Peter Hain said care must be taken not to alienate whole communities.
But Home Office minister Tony McNulty said there would be plenty of time for consultation and people should wait to see exactly what the new powers were.
The civil rights group Liberty's director, Shami Chakrabarti, said: "This looks like political machismo.
"Stopping and questioning anyone you like will backfire because people will be being criminalised."
Mr Hain, who is in the running to become Labour's deputy leader, told BBC1's Sunday AM programme that the UK must take care that its anti-terror legislation does not alienate whole communities, such as Muslims.
"We have got to be very careful that we do not create circumstances that are the domestic equivalent of Guantanamo Bay," he said.
"Guantanamo Bay, which was an international abuse of human rights, acted as a recruiting sergeant for dissidents and alienated Muslims and alienated many other people across the world."
Shadow foreign secretary William Hague told the same programme that the Conservatives would consider the proposals on merit.
Liberal Democrat home affairs spokesman Nick Clegg warned it would only increase radicalism.
Ahmed Versi, editor of Muslim News, a newspaper for British Muslims, said that extending police powers would be "counter-productive" in the effort to improve relations with Muslims and could drive some towards extremists.
Islamic Human Rights Commission chairman Massoud Shadjareh said it was essential to separate security issues from the "politics of fear".
The new legislation would be similar to that already used in Northern Ireland.
Police are still likely to need a "reasonable suspicion" a crime may be committed. Anyone refusing to co-operate could be fined up to £5,000.
At present, under section 44 of the Terrorism Act 2000, officers already have the power to stop and search people or vehicles in an area seen as being at risk from terrorism, even if they are not suspected of any breach of the law.
A Home Office spokeswoman said that the new proposals would give officers an automatic right to stop and question anyone in the UK about suspected terrorism.
Mr McNulty, the counter-terrorism minister, told BBC Radio 4's The World This Weekend the government would reveal its proposals to Parliament in the next couple of weeks.
He said: "There will be plenty of time to consult with a whole range of people before introducing such a bill - probably as late as October, November."
Labour chairwoman Hazel Blears, who is also a deputy leadership candidate, said the proposal was "reasonable".
When it emerged on Thursday that three men suspected of wanting to kill UK troops had disappeared, Mr Reid criticised his political opponents and judges for stopping the use of tougher measures against terror suspects.
He promised new anti-terror measures and told MPs that the government could consider suspending some parts of the European Convention on Human Rights (ECHR) so it can impose tougher control orders.
Greater powers to remove vehicles and paperwork for inspection are also believed to be part of the measures.
Writing in the Sunday Times, Tony Blair said the disappearance of the three suspects under control orders was a symptom of a society which put civil liberties before fighting terror, and that was "misguided and wrong".
He said: "If a foreign national comes here, and may be at risk in his own country, we should treat him well. But if he then abuses our hospitality and threatens us, I feel he should take his chance back in his own home country."