The poll of more than 2,000 British adults was conducted in October 2007, a month before the news broke of HM Revenue & Customs' loss of the personal details of 25 million child benefits claimants.
Respondents saw the potential role of the NIS in fighting terrorism, crime and fraud as most important, it said. Six out of 10 respondents were in favour of it.
Even so, "Across the board, full buy-in and belief in the scheme's ability to deliver the proposed benefits is weak," it said.
Fewer than three in 10 respondents found any of the eight main proposed benefits of the system "very believable". People had most confidence in the scheme's ability to make it easier for police to trace suspects and to ensure that people in positions of trust (e.g. nannies, school and care workers) were who they said they were.
Six out of 10 said the most likely benefits were to protect people against identity fraud, to stop illegal immigrants from finding work in the UK, and to make it easier for police to trace and identify suspects.
Compared to a similar IPS poll in February 2007, overall awareness of the NIS was down slightly (86% vs 91%). It was particularly low amongst young adults (68%) and ethnic minorities (70%). Those who knew of the scheme also knew it involves recording biometric details, but there was some confusion as to what this actually meant.
Asked why the government wanted to introduce the NIS, people said it was to prevent illegal immigration (32%, up from 23% in February), to make it easier to identify people, and to prevent fraud. Disrupting terrorists was fifth, making it easier to identify yourself was seventh, and stopping benefit fraud was ninth.
Four of 10 respondents were split evenly against the scheme or had no opinion. Objectors said it would infringe their personal freedom (33%), not work (25%) and would be too expensive or a waste of money (24%).