Simon Bridges is smarting after he was invited to attend an infrastructure conference held by the Government's Infrastructure Commission only for his invitation to be withdrawn after Shane Jones' office became involved.

Bridges is now accusing Jones of politicising that process by keeping him away from the an important conference during election year.

The "Infrastructure 2020: Looking Ahead" conference was organised by the New Zealand Infrastructure Commission, a Government agency established to give certainty to infrastructure providers by creating a list of infrastructure projects that the Government is confident it will build.

The pipeline is meant to be relatively non-partisan. National backed the Commission through Parliament and has pledged to support it after the election.

"Shane Jones has once again used his position as Minister for highly political purposes," Bridges said.

But Jones was unapologetic.

"For a mercifully brief period of time the prospect of Simon Bridges speaking hung by a thread and then a pair of secateurs came along and it was cut," Jones said.

Bridges was not impressed.

"Jones' motives are often questionable - whether it's using his slush fund to try to buy votes or trying to silence other political parties in an election year," he said.

But Jones says it would be inappropriate for the opposition leader to speak, given that the conference will be the setting for a Government announcement. Opposition leaders don't typically attend Government announcements.

He told Bridges, via a written Parliamentary question, that discussions with his staffers determined that "while it was appropriate to extend an invitation to the Opposition Infrastructure Spokesperson, it was not a suitable event for the Leader of the Opposition, Hon Simon Bridges, to speak at [the conference].

Jones also told Stuff that "any suggestion there was manipulation is wrong".

On 16 January, the Commission invited Bridges to speak at it's infrastructure conference, which kicks off this Friday.

"We, and I am sure our audience of ~140 infrastructure stakeholders, would be most interested to hear the National Party position on infrastructure as we get the year, and the Commission's strategy development work underway," the invitation said.

WARWICK SMITH/STUFF Regional Economic Development minister Shane Jones has rescinded Simon Bridges' invitation to an infrastructure conference.

Documents released to National under the Official Information Act confirm the Commission had initially pencilled in a speaking slot for Bridges.

But just days later, on 21 January, one of Jones' Beehive staffers raised concerns with Bridges' invitation to speak .

"I'll need to check with the boss about whether he's happy for Simon Bridges to talk. I'm not sure it's the right setting to be honest," she wrote.

Another staffer replied, "definitely not the right setting for Bridges".

The schedule was amended, Bridges speaking slot removed and the invitation rescinded.

Bridges' office was called and told that while Bridges would not be welcome, National's infrastructure spokesman Paul Goldsmith would be invited, although not to speak.

"The leader of the opposition has got many months to go campaigning and electioneering — this event was also conceived as an opportunity to be made about capital allocations for regional infrastructure projects

"This was never a central casting opportunity for political bit players to get a starring role," Jones said.