The Prime Minister says the whole process of investigation into New Zealand First's finances has been tainted from the outset.

Helen Clark says the privileges committee process has been totally unsatisfactory in terms of any natural justice. She says for that reason she is unlikely to be forced into a decision over Winston Peters this week. She says it has become so politicised with some MPs going into committee with made up minds before they had even heard a single piece of evidence.

However, Miss Clark very much doubts there will be anything to justify Mr Peters' reinstatement. She intends to continue burning the midnight oil doing his old job as Foreign Minister.

But the Prime Minister's comments have seen a swift response from the opposition. John Key says it is ridiculous for Helen Clark to claim the Parliamentary Privileges investigation into New Zealand First is tainted by politics.

National's leader says, while the Privileges Committee is, and always will be, made up of politicians, there is not the slightest hint of politics interfering with its business. He says although the chairman is National MP Simon Power, Mr Key has had no discussions with him about what is going on with him on the committee.

Mr Key says Owen Glenn's evidence to the committee was backed up by support documents and the people who have been changing their story are Winston Peters and his lawyer Brian Henry.

The Serious Fraud Office is reporting progress as it continues investigations into New Zealand First's handling of political donations. While it has now been three and a half weeks since the SFO announced it would undertake investigations to see if donations from Sir Robert Jones and the Vela Brothers reached the party as intended, SFO director Grant Liddell's office, in an e-mail, says the investigation is proceeding expeditiously.

However, the SFO is giving no timeline for when it might make an announcement about the outcome of its work.

Meanwhile, Parliament's Privileges Committee sits for what is expected to be the final time today before releasing findings on the pecuniary interests complaint made against Mr Peters. Those findings are expected to be discussed in Parliament tomorrow.