The NZ First leader stunned a parliamentary select committee on Wednesday when he asked Mr Dunne whether he was behind the leak, and followed up with "my assertion is that you did leak the report".
Mr Dunne, who was there to answer questions about the tax regime, categorically denied leaking the report garage storage cabinets
"It's a scurrilous stunt, I don't know what's behind it," he told reporters.
Prime Minister John Key has accepted Mr Dunne's word and as good as told Mr Peters to put up or shut up.
"If Winston Peters has evidence, then show us," he said.
"He is using parliamentary privilege to say something he didn't have the courage to say outside."
Select committee proceedings are covered by parliamentary privilege and Mr Dunne can't sue Mr Peters for defamation.
Challenged by reporters to produce evidence, Mr Peters replied: "That's what we do invest hong kong
. These are inquiries you should have made, if you can't do your job I'll do it for you."
The report by cabinet secretary Rebecca Kitteridge revealed the GCSB may have illegally spied on 88 New Zealanders.
It was leaked to Fairfax Media last month, while Mr Key was in China, and the government had to bring forward the official release date.
Former senior public servant David Henry was appointed to head a leak-hunting team and Mr Dunne confirmed he had been interviewed "the same as everyone else".
But some cabinet ministers told media neither they nor their staff had been questioned by Mr Henry.
His chief of staff, Rob Eaddy, saw the report and has also denied leaking it.
It was circulated to senior ministers and top government officials.