There were at least 44 infrastructure projects awaiting Green Party co-leader James Shaw's approval when he emailed ministerial colleagues to draw a line in the sand over the Green School.

The projects are collectively worth about $1.3 billion, of which the Government contribution is earmarked at $600 million.

Shaw is now being accused of "hypocrisy" and "disgraceful" tactics by the Opposition for potentially putting that funding and hundreds of jobs at risk by appearing to refuse to sign off the projects unless the private school was included.

Yesterday Shaw apologised for his "error in judgment" in advocating for the $11.7m funding for the school, but added that it wasn't an offence worth resigning over.

That was before an email - obtained by Newshub - surfaced that went to Government ministers and the Treasury from Shaw's office last month.

"Minister Shaw won't sign this briefing [of infrastructure projects] until the Green School in Taranaki is incorporated," the email dated August 7 said.

"Sorry to be the spanner-in-the-works, but if we can get the project included, he'll sign everything this afternoon."

Projects in the Government's $3 billion infrastructure fund need approval from Shaw, who is Associate Finance Minister, Finance Minister Grant Robertson, Associate Finance Minister David Parker, and Infrastructure Minister Shane Jones.

Robertson said the email from Shaw's office was not about all of the projects in the $3b fund because some had already been approved.

His office later confirmed that 118 projects had been signed off at the time of the email, and 162 projects were approved by August 28, meaning at least 44 projects were pending final approval when the email was sent.

Comparing the list of approved projects from August 6 and from August 28 reveals that Government funding for those 44 projects totalled just over $600m.

Robertson wouldn't be drawn on whether the email amounted to a threat from Shaw.

"He used those words and he has to be responsible for them.

"The whole [$3b] project wasn't at risk. We were continuing the process of tidying up the loose ends.

"Clearly he put his view forward very strongly. It is the nature of Coalition Governments that different parties will put their views forward."

Meanwhile, the CEO of Taranaki's Green School has spoken out in the wake of the backlash. Chris Edwards told Heather du Plessis-Allan they were a little bewildered when Shaw starting backing away.

"I think in our case, we going to keep our heads up, not curl up in a ball and cry and feel sorry for ourselves.

"We did that on good faith, we were told we did very well, we were one of the 150 funds offered, and we were told we were actually one of the best applications."