Key Points:

A law to protect MPs' rights to spend taxpayer money on advertising during the election campaign passed its next step last night, as National MPs accused the Government of riding roughshod over the long-held convention of seeking wide political support for electoral laws.

The bill extends until 2009 the current laws which allow MPs to use parliamentary funds for "communications" - such as advertisements and pamphlets - as long as they do not explicitly tout for votes, donations or party memberships.

However, it goes further than current law - effectively authorising public funds to be used for publications such as Labour's 2005 pledge card, which the Auditor-General deemed to break the rules for parliamentary funded advertisements at the last election.

In Parliament yesterday, National continued its attack on the bill as it went through the committee stages and was set down for its final reading on Tuesday.

National MP Tony Ryall said consensus was essential to ensure electoral laws were durable and did not change every time there was a change of Government.

He said National had ensured it had Labour's support for the electoral laws which introduced the MMP system in 1993 and 1994.

"I would like the minister to answer why we can't have that this time. Electoral law in this country has been developed on a bipartisan process over many, many years ... We shouldn't have a situation where every victor can write electoral laws to suit themselves."

Labour minister Michael Cullen said the law simply maintained the status quo until a permanent solution was found, and clarified what most parties had always understood it to cover.

He said National had used parliamentary funds for publications close to electioneering and pointed to examples of National Party newsletters bearing the Parliamentary crest and including words such as "my commitment to you" and "Nick for Nelson".

He said it was impractical to stop MPs using the public purse to communicate with constituents, and such communications were by their very nature political.