'Damning' Monis letter cover-up: Labor

Labor is accusing the government of covering up an error about the botched handling of a letter from Sydney siege gunman Man Haron Monis.

New documents show Prime Minister Tony Abbott's office knew Julie Bishop had inadvertently relied on incorrect evidence to tell parliament the gunman's letter to the attorney-general's department was sent to a high-level review, three days before the foreign minister corrected the record.

Ms Bishop told parliament after question time on June 4 her statement the week before was based on evidence from a departmental official.

She added that the letter was not given to the Sydney siege review as stated because of an administrative error.

Labor says the documents prove officials were aware Ms Bishop had misled the parliament but did nothing.

They claim they also reveal discussions were underway between the offices of the prime minister and the attorney-general about how to cover up the error.

"This evidence is damning," Labor frontbencher Penny Wong said in a statement on Friday.