Key Points:

Labour leader Phil Goff yesterday called on Prime Minister John Key to "come clean" on what he plans to do with the New Zealand Superannuation Fund.

His comments were sparked by Mr Key's refusal on Monday to comment on whether the Government contributions to the $12 billion fund should be suspended.

Further comments by Mr Key yesterday to TV3 are likely to fuel speculation that the Government is considering freezing the fund - which was established by former Finance Minister Michael Cullen and is sometimes called the Cullen Fund.

Mr Key said the Government always had the ability to consider its options and people were debating the merits of the Government having to borrow to fund its contribution this year. "That's a logical thing to do," he said.

A spokesman for Finance Minister Bill English said yesterday: "As the Prime Minister said yesterday, the issue has not been discussed at Cabinet. Therefore the Government's position has not changed and we expect contributions to continue."

But Mr Goff said Mr Key's unwillingness to rule out significant changes should worry New Zealanders.

He said the Super Fund was "a long-term game with long-term benefits to New Zealand".

"Tinkering with it by reducing the Government investment levels will only lead to reduced entitlements for future generations."

Those in their 30s, 40s and 50s today could be at "extreme risk" of being left short in their retirement, Mr Goff said.

National campaigned on a policy of keeping the fund and of requiring it over time to have at least 40 per cent of its investments in New Zealand.

The fund was set up to partially fund the superannuation bill for the country as the number of its aged increases.

It was estimated to grow to $100 billion by 2025. The Government has promised to keep the rate of entitlement of the pension and the age of eligibility at 65. It has cut the benefits to the voluntary KiwiSaver scheme to part fund its tax cuts.