The Governor-general, General Sir Peter Cosgrove was locked down during the Nice attack. Picture: Kym Smith

THE Australian embassy in Paris was put under virtual lockdown as the terror attack in the south of France unfolded, with a host of dignitaries including the Governor-General Sir Peter Cosgrove trapped in the building unable to leave.

News Corp Australia has learnt of extraordinary scenes at the diplomatic post which had been hosting an evening soiree to celebrate Bastille Day.

Sir Peter and his wife Lynne, NZ Prime Minister John Key and his wife Bronagh and several state governors and partners and French dignitaries were at the formal reception hosted by Australian ambassador Stephen Brady and his partner.

Australian Governor-General Peter Cosgrove and French President Francois Hollande attend from the presidential box on the Place de la Concorde, the annual Bastille Day military parade on the Champs Elysees avenue on July 14 in Paris. Picture: GettySource:Getty Images

The event was wrapping up and guests making to leave when unbeknown to them the Nice attack was unfolding.

The French tactical command descended on the embassy and said they couldn’t leave revealing there was a terror attack underway.

A large television at the ambassador’s residence was then switched on for guests as the harrowing live broadcasts of Nice were shown.

The French police did not allow any guests to leave before an “all clear safe to proceed” order was given from their security commanders about 12.45am.

The mood in the diplomatic post was said to be sombre with celebratory alcohol no longer consumed as events unfolded and the toll rose.

“The seriousness of what was happening was clear to all,” a local French attendee said.

People walk past a tribute to the victims of the Bastille Day Terror Attack on the Promenade des Anglais in Nice, France. Picture: GettySource:Getty Images

Australia had been nominated as France’s guest of honour at this year’s Bastille national day. The honour was in recognition of Australians historically supporting the French, with this week marking 100 years since its first battle in France in World War I.

The grand honour meant ANZAC troops of Australia and New Zealand led the military parade in central Paris.

The GG flew out of France the morning after the locked down reception.

The Department of Foreign Affairs and Trade declined to comment.