LONDON - Only a small minority of bodies consulted over proposals to allow police to detain terrorism suspects for up to 42 days without charge support the government's proposal, Home Secretary Jacqui Smith said on Tuesday.

The admission to a cross-party parliamentary committee came as Smith defended the controversial plans, which would increase the time suspects could be held from 28 days.

In her evidence to the Home Affairs Select Committee, Smith said that of 71 unnamed organisations which had given their opinion, just six had voiced "unequivocal" support.

While Smith refused to name any of the organisations or people, both the Director of Public Prosecutions, Ken Macdonald, and the former Attorney General, Lord Goldsmith, have given evidence to the committee saying no change was necessary.

Smith told the hearing that she had not met MacDonald to discuss the proposals despite needing his support.

Media reports at the weekend also said that the head of MI5, Jonathan Evans, privately told MPs that he would not back the new laws.

However senior police officers, including London Commissioner Ian Blair, have backed the extension. Smith argued the proposals were necessary to give police extra time to question suspects in highly-complex terrorism cases.

She said the laws would include "safeguards" with any application to extend the time needing support from both parliament and a judge.

Under questioning from opposition and government members, Smith denied the 42 day-limit had been formulated with political interests in mind but to "ensure successful prosecutions".

"It is likely there is a point in the future that with only 28 days we risk a situation that somebody would be released before the evidence was developed against them," she told the hearing.

She had previously agreed with her critics that there was no need to extend the time, but she said her opinion had changed in the current climate of sustained terrorism threats.

"If I am wrong, if senior police are wrong about holding somebody longer than 28 days, then the pre-trial extension would never be used," she said.

Smith unveiled the plans in a surprise announcement last week prompting heavy criticism from opposition parties, human rights groups and some Muslim organisations.

The level of opposition -- including from some government MPs -- indicates that Smith and Prime Minister Gordon Brown will face a tough battle to get the laws through parliament.

That would mirror the problems of former Prime Minister Tony Blair who suffered his first Commons defeat in 2005 when he tried to increase the detention time to 90 days.