Thousands of people dressed in white gathered in front of the Louvre museum for an "impromptu picnic" on Thursday evening (11 June).

Guests arrived from Parisian streets carrying tables, chairs and baskets full of fine food and wine.

The exclusive, invite-only Diner en Blanc – or Dinner in White in English – is organised every year with the location remaining a closely guarded secret until the last minute to keep diners and the authorities in the dark.

Organisers say while they are not officially allowed to put on a dinner, they are allowed to hold an impromptu picnic – hence the all-important secrecy.

But the event does not look like a makeshift affair, with thousands dressed to impress sitting at tables covered in crisp white tablecloths and crowned with candelabras.

Once everyone is ready, guests traditionally swing their white cloth napkins as a sign indicating the start of the dinner. Other codes ask that guests leave the place as clean as they find it.

"This is pure pleasure, we are in an incredible and exceptional place and to have this chance to have dinner here, it is an improvised picnic, it's quite unbelievable. It's half improvised really, there's quite a bit of preparation really, but its great pleasure," said Parisian Thierry Millet.

The event is held annually at a different Parisian monument. But this year, last minute confusion pushed guests from the Cour Carrée in the centre of the Louvre to the Tuileries gardens.

Still, with the famous Louvre pyramid and the Eiffel Tower in the distance as backdrops, guests were not disappointed.

"Tonight is the incarnation of French excellence, despite France being well or not, this moment allows us to take our breath, it's a safe haven," said Parisian Titus.

The idea has also proved popular abroad with organisers saying close to 70 other events are scheduled for 2015 mostly in North America and Europe. After Paris, the biggest gathering is Montreal in Canada.