Prime Minister Tony Abbott's office knew Foreign Minister Julie Bishop had misled Parliament about Sydney siege gunman Man Haron Monis three days before the government eventually owned up to the mistake.

The delay in correcting the parliamentary record until the end of a sitting fortnight meant the government faced no scrutiny in question time over its handling of the case.

Prime Minister Tony Abbott and wife Margie lay a bouquet of flowers outside the Lindt cafe.

The newly released, heavily redacted documents show Mr Abbott's office knew Ms Bishop had relied on false evidence to defuse Labor's line of attack about why the letter from Monis to Attorney-General George Brandis had not been taken seriously.

In the letter, Monis asked if it was lawful for him to contact the leader of Islamic State. Senator Brandis' office drafted a routine reply, despite Australia's terror threat level being lifted to "high" just weeks earlier.