A tribute to the victims of the fatal Sydney siege will be installed in the Lindt cafe before it reopens.

Repairs are under way at the Martin Place site, which has been closed since the siege in mid-December.

A decision on when the cafe will open its doors is due to be made next week, a company source told AAP on Wednesday.

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”There are some serious practical considerations to work through,” he said.

Cafe manager Tori Johnson and Sydney barrister Katrina Dawson were killed during the 16-hour siege, along with gunman Man Haron Monis.

“There will be a tribute, a plaque or something,” a Lindt employee told AAP.

Prime Minister Tony Abbott on Wednesday received an official report into the tragedy and has promised to release it by the end of the month.

“Plainly the Martin Place murderer took advantage of our system. That’s what this report is designed to expose to us and we will take the strongest possible action to ensure this can’t happen again,” he said.

It was revealed at a coronial inquest last week that Mr Johnson was shot in the head by Monis after being forced to kneel on the cafe floor.

Ms Dawson was killed by fragments of ricocheting bullets fired by police as they stormed the cafe.