Trading on Australia's key financial markets has been hit by the hostage crisis in Martin Place.
Australia's major banks were forced to shut down their branches and offices in Sydney's CBD in response to the siege at the Lindt Chocolat Cafe, where an unknown number of people were taken hostage on Monday morning.
With many traders locked out of their offices, volumes on financial markets were lower than usual.
Commonwealth Bank fixed income strategist Philip Brown said the evacuation of his Sydney colleagues, and banking analysts from rival firms, had led to reduced trading volumes.
"A large number of people have either been asked to go home or just decided to set off because with no public transport and no way to cross the Harbour Bridge, it takes people a long time to get home," he told AAP from Melbourne.
Trading volumes of three-year Commonwealth government bond futures dropped below 95,000, or by more than a third from the usual trading level of about 150,000, he added.
Trading volumes on the stock market were also weaker.
"The futures and options expire this week but volumes are surprisingly low and I suspect that has a lot to do with the fact that Sydney's CBD is like a ghost town at the moment," CMC Markets chief market strategist Michael McCarthy said.
The big four banks - the Commonwealth, Westpac, ANZ and National Australia Bank - shut their CBD branches as police taped off the area around the cafe.
The Commonwealth evacuated customers from its branch at 48 Martin Place and locked it down.
Macquarie Group relocated staff from its headquarters at 50 Martin Place to other parts of the city and instructed others to work from home.
Meanwhile, the Reserve Bank of Australia, which is located across the street from the cafe, continued operating with back-up procedures in place.
Treasurer Joe Hockey said he had been in contact with RBA governor Glenn Stevens on several occasions on Monday.
"Operational matters are being appropriately taken care of," he told reporters in Canberra.
