The Evening Standard newspaper said the Intelligence and Security Committee will say Geoff Hoon misled its investigation into the arguments for war on Iraq.
If true, it was likely Hoon would offer his resignation.
But another newspaper, The Times, said the report would not be as damaging to Hoon as an earlier leak had suggested.
The British media is almost unanimous that Hoon's career will not survive an inquiry into the suicide of weapons scientist David Kelly.
The scientist killed himself in July after being named as the source for a reporter's claim that politicians "sexed up" intelligence to justify war.
Thursday will see the publication of the findings of a separate, earlier probe into the justification for war, carried out by the Intelligence and Security Committee.
The Evening Standard said the committee would accuse Hoon of misleading it by denying that his ministry's spies had expressed doubts about some claims the government made in arguing for war.
David Kelly killed himself after
being named as a source for a
The United States and Britain led the invasion of Iraq in March, accusing president Saddam Hussein of developing weapons of mass destruction.
No such weapons have been found.
Defence intelligence officials have since testified in the Kelly probe that they had doubts about the weapons' claims and made their doubts known.
Opponents of British Prime Minister Tony Blair have focused not only on the committee's reportedly leaked findings, but on the leak itself, saying they believed Blair's office was trying to pile blame on Hoon to deflect criticism of others.
But Blair has denied that his staff was behind the leak.