The Federal Government has declared last month’s Sydney siege a “terrorist incident” to ensure affected businesses can receive insurance payouts.

Gunman Man Haron Monis stormed Martin Place’s Lindt Cafe on December 15, holding 18 people hostage for up to 16 hours, which ended with the deaths of cafe manager Tori Johnson and barrister Katrina Dawson.

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Treasurer Joe Hockey said the declaration prevents insurers from refusing claims if their policies exclude losses from acts of terrorism.

“The Government has taken this action to ensure businesses that suffered damages from the incident will not be denied claims due to terrorism exclusions in their insurance policies,” he said.

“Advice from the Australian Reinsurance Pool Corporation (ARPC) indicates the three insurers that have registered claims to date have stated they will not apply terrorism exclusion clauses.

“I am pleased to see these companies acting so responsibly at this difficult time.”

Mr Hockey said he has been advised that the businesses affected by the incident have made claims totalling around $600,000.

An inquest into the deaths of Mr Johnson, Ms Dawson and Monis will open for public hearings on January 29.