Striking workers at the National Gallery of Canada are asking the public not to buy tickets to the gallery's big summer show.

A retrospective of the work of Austrian painter Gustav Klimt opens on Friday.

The striking employees held a mock launch outside the gallery on Wednesday, while the media previewed the show inside.

It's the first solo exhibition of Klimt's work to be mounted in North America.

Support workers from the National Gallery of Canada and the Museum of Contemporary Photography have been on strike for almost five weeks.

The main issue in the dispute is money.