The biggest week for corporate Christmas parties is in chaos today following the terrorist siege in Martin Place, with many buildings in the CBD in lockdown and the Opera House closed.

The Dockside Group’s Christine Drivas reports no cancellations at this stage but plenty of calls from concerned parents relating to a school formal this evening.

Nicole Friedler from Captain Cook Cruises says there have also been no cancellations, however, they have a large corporate event tonight with a nervous client considering a cancellation.

Steve McCarthur reports O Bar and Dining Sydney at the top of Australia Square has closed for the day “for the safety of staff and patrons”.

The Hilton Sydney’s Florencia Aimo reports one event has been cancelled at the hotel and there have been cancellations at glass brasserie for lunch today.

Australian Technology Park’s Ruby Chronis reports site inspections have been cancelled today. Australian Turf Club at Randwick and Luna Park both report it is business as usual.

The Westin’s Charlotte Roderick said the situation is currently confined to upper Martin Place and is not impacting the hotel which is located at the bottom of Martin Place.

The SMH reports online there have been disruptions to the launch of the NRL 2015 season draw and the launch of Netball Central – the new Netball NSW centre in Homebush.

A walk through the city has shown longer than usual bus queues with many workers believed to be going home, quiet streets, and a significantly smaller amount of shoppers out at lunchtime with numerous streets closed in the heart of the CBD.

Pictured above is the crowd gathered at Martin Place a short time ago.