Gallant said concerns about the support for Atcon have been well discussed for years and he won't support calls for a further examination.
"Given that her report has found no new information, and the auditor general herself has suggested we have already spent much money and time on this issue, we will not support a forensic audit," Gallant said.
On Tuesday, auditor general Kim MacPherson said the Economic Development Department, under the government of then-premier Shawn Graham, provided $50 million in loan guarantees to Atcon in June 2009 on cabinet approval despite senior staff recommendations to reject the request for assistance.
MacPherson said the cabinet exercised a "very troubling disregard for taxpayer's money."
She said she'd be willing to conduct a forensic audit if asked and provided with the money needed to do the work.
Tory justice critic Hugh Flemming tabled a motion Wednesday calling on the government to request such an audit, saying there are still many questions to be answered, including where the public money went.
"Is there accountability for some of this stuff?" Flemming asked.
MacPherson's report concluded that taxpayers in New Brunswick were left on the hook for nearly $70 million as a result of government support for Atcon, which filed for creditor protection in 2010.
Gallant said he will work with the auditor general to see that her recommendations to improve fiscal accountability are implemented.
For the second day in a row, six current cabinet ministers who were in Shawn Graham's cabinet at the time of the Atcon decisions declined to speak with reporters. Instead, Gallant — who was not part of the Graham government — was made available to speak on their behalf.
"I'm the premier of the province and I'll take your questions on any file that I think I can shed any light on," he said.
The Progressive Conservatives have called for the six ministers to be fired. But Gallant defended them, saying they were re-elected in 2010 and 2014 despite reports in the public about the money lost to Atcon.
"The people of New Brunswick elected these people to represent them with no asterisk saying, 'We're going to elect them but don't put them in cabinet,'" Gallant said.