The Government has ordered another witch-hunt after more leaking of sensitive documents - this time from the Ministry of Pacific Island Affairs, which questioned whether an inexperienced private company was a good choice for $4.8 million in funding.

Two other investigations are already under way into the source of leaks; the first was the Government's proposal to mine land protected in Schedule Four of the Crown Minerals Act; the second was plans to restructure the public service and merge Archives New Zealand and the National Library into the Department of Internal Affairs.

Pacific Island Affairs chief executive Colin Tukuitonga said an independent investigation would look at how a ministry briefing for minister Georgina te Heuheu on the Budget fell into the hands of Radio New Zealand.

"I need to assure myself, and our minister, that our staff have acted appropriately and in accordance with the state services standards of integrity and conduct," Dr Tukuitonga said.

The briefing outlined criticisms about the Pacific Economic Development Agency (Peda), which is finalising a purchase agreement with the Government to secure $4.8 million over four years for projects to lift Pacific people.

Radio NZ said the ministry's advice to Mrs te Heuheu was that Peda was "untested and unproven", had "not delivered on projects of any note", and "does not have a good record of working collaboratively with other agencies".

The ministry also said: "The inability to tender for an appropriate provider or range of providers capable of delivering these initiatives may be inconsistent with Government procurement procedures."

Mrs te Heuheu has said ministries always provide advice, but it is up to the minister to decide how to respond, including whether to ignore some advice.

The Government, which has conceded that there was no tender process for the funds, has been heavily criticised over Peda.

It has said no money will be handed over until a robust purchase agreement with Peda can be reached. If it cannot, other agencies will be invited to compete for the funds.

Up to six Government departments have already been scrutinised in the hunt for the sources of leaks in the first two investigations.