Established in 2008, Jamie Oliver Restaurant Group operates premium brands in the restaurant sector including Jamie's Deli, Jamie Oliver's Diner, Jamie Oliver's Pizzeria and Jamie's Italian.
The assurances were made despite reports that the Jamie Oliver Restaurant Group (Australia) Pty Ltd collapsed on Monday.
The celebrity chef's United Kingdom restaurants have been in financial strife amid rising costs and consumer caution, partly as a result of the Brexit vote, and his Canberra venue has now been closed.
In a statement via social media the Canberra restaurant said: "This is pretty sad news for the staff but Jamie's Italian has closed suddenly this morning and it looks like it won't be reopening anytime soon".
"Australia has and continues to be one of our best performing global markets", Mr Shaughnessy said.
"We'll be working closely with Jamie and the United Kingdom team, staff and local suppliers to keep driving the business forward and delivering exceptional experiences across the country", a statement by Hallmark said.
Celebrity chef Jamie Oliver took control of his Australian holdings a little over 12 months ago, buying his six Jamie's Italian restaurants from the receivers of the failed Keystone Group, but since then, Oliver's United Kingdom interests have run into trouble.
The business entered a company voluntary arrangement that allowed some UK Jamie's Italian restaurants to continue to trade, but there were other casualties, including the flagship operation of Oliver's steak restaurant concept, Barbecoa.
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