A VEIL of secrecy has been thrown over the filming of a beer ad in Swan Hill.

Popular tourist attraction, the Pioneer Settlement has been closed to visitors since yesterday to allow shooting of the ad which is set in the 1800s and will be screened on television in the United Kingdom.

About 100 locals have been recruited as extras to work alongside another 50 cast and crew members on the set in the settlement's main street and Lower Murray Inn.

Local media had been granted approval to record and photograph some of the action, but permission was withdrawn yesterday by the Sydney-based advertising firm.

One photographer who visited the site was then reportedly instructed to delete all images on their camera, including some from a previous unrelated assignment.

''Commercial confidence'' was cited as the reason for the change of heart.

Not even the name of the beer – which does not retail in Australia - has been made public.

Apparently the international beer market is so cut-throat that a competitor who found out about the ad might rush out to make something similar for their product as a ''spoiler''.

Australia's first outdoor folk museum, the settlement was opened in 1963 by then Victorian Premier Henry Bolte.

It recreates life in the Murray-Mallee between 1830 and 1930.