The attorney general has revealed that cabinet colleagues were consulted about the "Stormontgate" affair.
Devolved government collapsed in October 2002 after police raid
Lord Goldsmith said they were asked whether they had "information that might bear on the consideration of the public interest by the DPP".
However, he said the information obtained from ministers played no part in the decision to drop the charges.
The revelation was made in a letter to DUP leader Ian Paisley, who said he was still pressing for a full explanation.
Northern Ireland's power-sharing executive collapsed in October 2002 following the arrests of three men, including Denis Donaldson, who had headed Sinn Fein's administration office at Stormont.
Charges against the three were dropped earlier this month after the prosecution offered no evidence "in the public interest".
A week later, Mr Donaldson was expelled from Sinn Fein. He admitted he had worked as a paid British agent since the 1980s.