Banning the public and the media from hearings on a new law increasing the powers and reach of the Security Intelligence Service is a giant leap backwards.

And not just to the Cold War era. It falls not far short of a return to the Dark Ages of parliamentary scrutiny - or rather the lack of it.

As the minister in charge of the SIS, the Prime Minister may have very good reasons for not allowing submissions on the New Zealand Security Intelligence Service Amendment Bill to be heard in public by Parliament's intelligence and security committee.

It would be useful if he shared them with the rest of the country.

Under its current director, Warren Tucker, the SIS has opened the door - if only very slightly - and shone some small light on its activities.

In doing so, it has demystified itself to some degree and aided public understanding of why security services are essential to the country's wellbeing.

That minor bit of good public relations risks being washed away by Key's ban.

The Prime Minister can do this because he chairs the committee and its proceedings are held in private unless it resolves otherwise - and such a resolution must be unanimous.

The committee was established in 1996 to give some parliamentary oversight of the SIS and the other security agency, the Government Communications and Security Bureau.

Its other members of the committee are Phil Goff as Leader of the Opposition plus Tariana Turia, Rodney Hide and Russel Norman as leaders or co-leaders of the Maori Party, Act and the Greens.

The committee's utterings have never been verbose.

It seems to function on a "you can trust us to ensure the spooks are behaving themselves" basis, rather than giving any information as to what is really going on.

The public will be able to make submissions on the bill and be able to make them public. But the committee will determine whether it wants to question such submitters. If so, that will happen in closed session.

Judging from Key's response to questions, few of those making submissions will be called to appear before the committee.

The Prime Minister says keeping the hearings in closed session is in the public interest. But he refuses to explain why.

Presumably it is because any detail of why the service needs the changes and how it intends to make use of them is deemed to be prejudicial to national security.

The secrecy and the rush is being attributed to the need to ensure the intelligence services have all the powers they need to counter any terrorists contemplating disrupting next year's Rugby World Cup.

But the secrecy runs counter to the way legislation is normally handled. Notably, the 2003 Counter Terrorism Bill went before Parliament's foreign affairs and defence select committee which heard 11 submissions in public.

What is needed is a comprehensive rewrite of the decades-old Security Intelligence Act done transparently, openly and without haste.

The Government has flagged such a rewrite, but the Prime Minister would not make a commitment yesterday to do it.

That starts to make the Rugby World Cup look less a good reason for increasing the SIS's powers to breach privacy supposedly protected by New Zealand's toothless Bill of Rights and more like a convenient excuse for doing so.